diff --git a/packages/api-codec/src/AccountId.ts b/packages/api-codec/src/AccountId.ts
index 06f811391384..914283fae856 100644
--- a/packages/api-codec/src/AccountId.ts
+++ b/packages/api-codec/src/AccountId.ts
@@ -9,16 +9,16 @@ import isHex from '@polkadot/util/is/hex';
 import isU8a from '@polkadot/util/is/u8a';
 import u8aToU8a from '@polkadot/util/u8a/toU8a';
 
-import CodecU8a from './codec/U8a';
-import CodecU8aFixed from './codec/U8aFixed';
+import U8a from './codec/U8a';
+import U8aFixed from './codec/U8aFixed';
 
 // A wrapper around an AccountId/PublicKey representation. Since we are dealing with
-// underlying PublicKeys (32 bytes in length), we extend from CodecU8aFixed which is
+// underlying PublicKeys (32 bytes in length), we extend from U8aFixed which is
 // basically just a Uint8Array wrapper with a fixed length.
-export default class AccountId extends CodecU8aFixed {
-  constructor (value: CodecU8a | string | Uint8Array = new Uint8Array()) {
+export default class AccountId extends U8aFixed {
+  constructor (value: U8a | string | Uint8Array = new Uint8Array()) {
     super(
-      value instanceof CodecU8a
+      value instanceof U8a
         ? value.raw
         : AccountId.decode(value),
       256
diff --git a/packages/api-codec/src/AccountIndex.ts b/packages/api-codec/src/AccountIndex.ts
index 6a08d36c49b6..11ec565d1fac 100644
--- a/packages/api-codec/src/AccountIndex.ts
+++ b/packages/api-codec/src/AccountIndex.ts
@@ -2,21 +2,18 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import hexToU8a from '@polkadot/util/hex/toU8a';
-import isHex from '@polkadot/util/is/hex';
-import isU8a from '@polkadot/util/is/u8a';
 import u8aToHex from '@polkadot/util/u8a/toHex';
 import u8aToU8a from '@polkadot/util/u8a/toU8a';
 
-import CodecU8a from './codec/U8a';
+import U8a from './codec/U8a';
 
 // A wrapper around an AccountIndex, which is a shortened, variable-length encoding
-// for an Account. We extends from CodecU8a which is basically
+// for an Account. We extends from U8a which is basically
 // just a Uint8Array wrapper.
-export default class AccountIndex extends CodecU8a {
-  constructor (value: CodecU8a | string | Uint8Array = new Uint8Array()) {
+export default class AccountIndex extends U8a {
+  constructor (value: U8a | string | Uint8Array = new Uint8Array()) {
     super(
-      value instanceof CodecU8a
+      value instanceof U8a
         ? value.raw
         : AccountIndex.decode(value)
     );
@@ -29,13 +26,7 @@ export default class AccountIndex extends CodecU8a {
   }
 
   static decode (value: string | Uint8Array | Array<number>): Uint8Array {
-    if (isU8a(value) || Array.isArray(value)) {
-      return u8aToU8a(value);
-    } else if (isHex(value)) {
-      return hexToU8a(value);
-    }
-
-    throw new Error(`Unable to decode AccountIndex for [${value.toString()}]`);
+    return u8aToU8a(value);
   }
 
   fromJSON (input: any): AccountIndex {
diff --git a/packages/api-codec/src/Address.ts b/packages/api-codec/src/Address.ts
index cd7abd9c9a16..57494d963dcb 100644
--- a/packages/api-codec/src/Address.ts
+++ b/packages/api-codec/src/Address.ts
@@ -7,7 +7,7 @@ import isU8a from '@polkadot/util/is/u8a';
 import u8aConcat from '@polkadot/util/u8a/concat';
 import u8aToU8a from '@polkadot/util/u8a/toU8a';
 
-import CodecBase from './codec/Base';
+import Base from './codec/Base';
 import AccountId from './AccountId';
 import AccountIndex from './AccountIndex';
 
@@ -16,7 +16,7 @@ import AccountIndex from './AccountIndex';
 // we extend from Base with an AccountId/AccountIndex wrapper. Basically the Address
 // is encoded as
 //   [ <prefix-byte>, ...publicKey/...bytes ]
-export default class Address extends CodecBase<AccountId | AccountIndex> {
+export default class Address extends Base<AccountId | AccountIndex> {
   constructor (value: Address | AccountId | AccountIndex | string | Uint8Array = new Uint8Array()) {
     super(
       value instanceof Address
diff --git a/packages/api-codec/src/Block.spec.js b/packages/api-codec/src/Block.spec.js
new file mode 100644
index 000000000000..26275324f9df
--- /dev/null
+++ b/packages/api-codec/src/Block.spec.js
@@ -0,0 +1,51 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import hexToU8a from '@polkadot/util/hex/toU8a';
+
+import Block from './Block';
+
+describe('Block', () => {
+  it('decodes a block properly', () => {
+    const block = new Block();
+
+    block.fromU8a(hexToU8a(
+      '0x' +
+      // parent_hash
+      '0900000000000000000000000000000000000000000000000000000000000009' +
+      // number
+      '4300000000000000' +
+      // state_root
+      '0800000000000000000000000000000000000000000000000000000000000008' +
+      // transaction_root
+      '0700000000000000000000000000000000000000000000000000000000000007' +
+      // digest
+      '08' + // 2 << 2
+      '0401' +
+      '0402' +
+      // transactions
+      '04' + // 1 << 2
+      // 111 bytes in compact encoding
+      'bd01' +
+      // prefix
+      'ff' +
+      '0000000000000000000000000000000000000000000000000000000000000000' +
+      '00000000' +
+      '0300' +
+      '7527000000000000' +
+      '0000000000000000000000000000000000000000000000000000000000000000' +
+      '0000000000000000000000000000000000000000000000000000000000000000'
+    ));
+
+    expect(
+      block.header.blockNumber.toNumber()
+    ).toEqual(67);
+    expect(
+      block.extrinsics.length
+    ).toEqual(1); // eslint-disable-line
+    expect(
+      block.extrinsics.at(0).length
+    ).toEqual(111); // eslint-disable-line
+  });
+});
diff --git a/packages/api-codec/src/Block.ts b/packages/api-codec/src/Block.ts
new file mode 100644
index 000000000000..92d8c0f99c22
--- /dev/null
+++ b/packages/api-codec/src/Block.ts
@@ -0,0 +1,27 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import Struct from './codec/Struct';
+import Vector from './codec/Vector';
+
+import Extrinsic from './Extrinsic';
+import Header from './Header';
+
+// A block encoded with header and extrinsics
+export default class Block extends Struct {
+  constructor (value?: any) {
+    super({
+      header: Header,
+      extrinsics: Vector.with(Extrinsic)
+    }, value);
+  }
+
+  get extrinsics (): Vector<Extrinsic> {
+    return this.raw.extrinsics as Vector<Extrinsic>;
+  }
+
+  get header (): Header {
+    return this.raw.header as Header;
+  }
+}
diff --git a/packages/api-codec/src/Bool.ts b/packages/api-codec/src/Bool.ts
index bbb05d8951a7..4a3b447c49a0 100644
--- a/packages/api-codec/src/Bool.ts
+++ b/packages/api-codec/src/Bool.ts
@@ -2,9 +2,9 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecBase from './codec/Base';
+import Base from './codec/Base';
 
-export default class Bool extends CodecBase<boolean> {
+export default class Bool extends Base<boolean> {
   constructor (value: Bool | boolean = false) {
     super(
       value instanceof Bool
diff --git a/packages/api-codec/src/Extrinsic.ts b/packages/api-codec/src/Extrinsic.ts
new file mode 100644
index 000000000000..516d4e40f2e3
--- /dev/null
+++ b/packages/api-codec/src/Extrinsic.ts
@@ -0,0 +1,22 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import blake2Asu8a from '@polkadot/util-crypto/blake2/asU8a';
+
+import Bytes from './codec/Bytes';
+
+import Hash from './Hash';
+
+// Representation of an Extrinsic in the system.
+//
+// NOTE At this point we are just keeping to a bare-bones Vec<u8> structure,
+// this should be expanded to do the automatic decoding of an extrinsic
+export default class Extrinsic extends Bytes {
+  // convernience, encodes the extrinsic and returns the actual hash
+  get hash (): Hash {
+    return new Hash(
+      blake2Asu8a(this.toU8a(), 256)
+    );
+  }
+}
diff --git a/packages/api-codec/src/H256.ts b/packages/api-codec/src/H256.ts
index 8c3fafe90e89..ab534091190b 100644
--- a/packages/api-codec/src/H256.ts
+++ b/packages/api-codec/src/H256.ts
@@ -2,13 +2,13 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecU8a from './codec/U8a';
-import CodecU8aFixed from './codec/U8aFixed';
+import U8a from './codec/U8a';
+import U8aFixed from './codec/U8aFixed';
 
 // Hash containing 256 bits (32 bytes), typically used in blocks, extrinsics and
 // as a sane default for fixed-length hash representations.
-export default class H256 extends CodecU8aFixed {
-  constructor (value?: CodecU8a | Uint8Array) {
+export default class H256 extends U8aFixed {
+  constructor (value?: U8a | string | Uint8Array) {
     super(value, 256);
   }
 }
diff --git a/packages/api-codec/src/H512.ts b/packages/api-codec/src/H512.ts
index 2c713a3ac720..4c12b7c3d64d 100644
--- a/packages/api-codec/src/H512.ts
+++ b/packages/api-codec/src/H512.ts
@@ -2,12 +2,12 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecU8a from './codec/U8a';
-import CodecU8aFixed from './codec/U8aFixed';
+import U8a from './codec/U8a';
+import U8aFixed from './codec/U8aFixed';
 
 // Hash containing 512 bits (64 bytes), typically used for signatures
-export default class H512 extends CodecU8aFixed {
-  constructor (value?: CodecU8a | Uint8Array) {
+export default class H512 extends U8aFixed {
+  constructor (value?: U8a | string | Uint8Array) {
     super(value, 512);
   }
 }
diff --git a/packages/api-codec/src/Header.ts b/packages/api-codec/src/Header.ts
index 3272e523d00f..1082bc59fb93 100644
--- a/packages/api-codec/src/Header.ts
+++ b/packages/api-codec/src/Header.ts
@@ -2,29 +2,45 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecArray from './codec/Array';
-import CodecBytes from './codec/Bytes';
-import CodecStruct from './codec/Struct';
+import BN from 'bn.js';
+import blake2Asu8a from '@polkadot/util-crypto/blake2/asU8a';
+
+import Bytes from './codec/Bytes';
+import UInt from './codec/UInt';
+import Struct from './codec/Struct';
+import Vector from './codec/Vector';
 
 import BlockNumber from './BlockNumber';
 import Hash from './Hash';
 
+type DigestStruct = {
+  logs?: Array<Uint8Array | string>
+};
+
+type HeaderStruct = {
+  digest?: DigestStruct,
+  extrinsicsRoot?: Hash | Uint8Array | string,
+  number?: UInt | BN | number | string,
+  parentHash?: Hash | Uint8Array | string,
+  stateRoot?: Hash | Uint8Array | string
+};
+
 // A block header digest.
-export class Digest extends CodecStruct {
-  constructor (value?: any) {
+export class Digest extends Struct {
+  constructor (value: DigestStruct = {}) {
     super({
-      logs: CodecArray.with(CodecBytes)
+      logs: Vector.with(Bytes)
     }, value);
   }
 
-  get logs (): CodecArray<CodecBytes> {
-    return this.raw.logs as CodecArray<CodecBytes>;
+  get logs (): Vector<Bytes> {
+    return this.raw.logs as Vector<Bytes>;
   }
 }
 
 // A block header.
-export default class Header extends CodecStruct {
-  constructor (value?: any) {
+export default class Header extends Struct {
+  constructor (value: HeaderStruct = {}) {
     super({
       parentHash: Hash,
       number: BlockNumber,
@@ -46,6 +62,13 @@ export default class Header extends CodecStruct {
     return this.raw.extrinsicsRoot as Hash;
   }
 
+  // convernience, encodes the header and returns the actual hash
+  get hash (): Hash {
+    return new Hash(
+      blake2Asu8a(this.toU8a(), 256)
+    );
+  }
+
   get parentHash (): Hash {
     return this.raw.parentHash as Hash;
   }
diff --git a/packages/api-codec/src/KeyValue.ts b/packages/api-codec/src/KeyValue.ts
index 088e9efd0870..a260e3240044 100644
--- a/packages/api-codec/src/KeyValue.ts
+++ b/packages/api-codec/src/KeyValue.ts
@@ -2,31 +2,31 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecBytes from './codec/Bytes';
-import CodecStruct from './codec/Struct';
+import Bytes from './codec/Bytes';
+import Struct from './codec/Struct';
 
 type KeyValueStruct = {
-  key: Uint8Array,
-  value: Uint8Array
+  key?: Uint8Array | string,
+  value?: Uint8Array | string
 };
 
 // KeyValue structure. Since most of the keys and resultant values in Subtrate is
-// hashed and/or encoded, this does not wrap a CodecString, but rather a CodecBytes
+// hashed and/or encoded, this does not wrap a Text, but rather a Bytes
 // for the keys and values. (Not to be confused with the KeyValue in Metadata, that
 // is actually for Maps, whereas this is a representation of actaul storage values)
-export default class KeyValue extends CodecStruct {
-  constructor (value: KeyValueStruct = {} as KeyValueStruct) {
+export default class KeyValue extends Struct {
+  constructor (value: KeyValueStruct = {}) {
     super({
-      key: CodecBytes,
-      value: CodecBytes
+      key: Bytes,
+      value: Bytes
     }, value);
   }
 
-  get key (): CodecBytes {
-    return this.raw.key as CodecBytes;
+  get key (): Bytes {
+    return this.raw.key as Bytes;
   }
 
-  get value (): CodecBytes {
-    return this.raw.value as CodecBytes;
+  get value (): Bytes {
+    return this.raw.value as Bytes;
   }
 }
diff --git a/packages/api-codec/src/Metadata.ts b/packages/api-codec/src/Metadata.ts
index f8218f81c898..eba07b54b674 100644
--- a/packages/api-codec/src/Metadata.ts
+++ b/packages/api-codec/src/Metadata.ts
@@ -2,13 +2,13 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecArray from './codec/Array';
-import CodecBase from './codec/Base';
-import CodecEnum from './codec/Enum';
-import CodecEnumType from './codec/EnumType';
-import CodecOption from './codec/Option';
-import CodecStruct from './codec/Struct';
-import String from './String';
+import Vector from './codec/Vector';
+import Base from './codec/Base';
+import Enum from './codec/Enum';
+import EnumType from './codec/EnumType';
+import Option from './codec/Option';
+import Struct from './codec/Struct';
+import Text from './Text';
 import Type from './Type';
 import U16 from './U16';
 
@@ -16,72 +16,72 @@ import U16 from './U16';
 // file is probably best understood from the bottom-up, i.e. start reading right at the
 // end and work up. (Just so we don't use before definition)
 
-class EventMetadata extends CodecStruct {
+export class EventMetadata extends Struct {
   constructor () {
     super({
-      name: String,
-      arguments: CodecArray.with(Type),
-      documentation: CodecArray.with(String)
+      name: Text,
+      arguments: Vector.with(Type),
+      documentation: Vector.with(Text)
     });
   }
 
-  get arguments (): CodecArray<Type> {
-    return this.raw.arguments as CodecArray<Type>;
+  get arguments (): Vector<Type> {
+    return this.raw.arguments as Vector<Type>;
   }
 
-  get documentation (): CodecArray<String> {
-    return this.raw.documentation as CodecArray<String>;
+  get documentation (): Vector<Text> {
+    return this.raw.documentation as Vector<Text>;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 }
 
-class OuterEventMetadataEvent extends CodecStruct {
+export class OuterEventMetadataEvent extends Struct {
   constructor () {
     super({
-      name: String,
-      events: CodecArray.with(EventMetadata)
+      name: Text,
+      events: Vector.with(EventMetadata)
     });
   }
 
-  get events (): CodecArray<EventMetadata> {
-    return this.raw.events as CodecArray<EventMetadata>;
+  get events (): Vector<EventMetadata> {
+    return this.raw.events as Vector<EventMetadata>;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 }
 
-class OuterEventMetadata extends CodecStruct {
+export class OuterEventMetadata extends Struct {
   constructor () {
     super({
-      name: String,
-      events: CodecArray.with(OuterEventMetadataEvent)
+      name: Text,
+      events: Vector.with(OuterEventMetadataEvent)
     });
   }
 
-  get events (): CodecArray<OuterEventMetadataEvent> {
-    return this.raw.events as CodecArray<OuterEventMetadataEvent>;
+  get events (): Vector<OuterEventMetadataEvent> {
+    return this.raw.events as Vector<OuterEventMetadataEvent>;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 }
 
-class FunctionArgumentMetadata extends CodecStruct {
+export class FunctionArgumentMetadata extends Struct {
   constructor () {
     super({
-      name: String,
+      name: Text,
       type: Type
     });
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 
   get type (): Type {
@@ -89,54 +89,54 @@ class FunctionArgumentMetadata extends CodecStruct {
   }
 }
 
-class FunctionMetadata extends CodecStruct {
+export class FunctionMetadata extends Struct {
   constructor () {
     super({
       id: U16,
-      name: String,
-      arguments: CodecArray.with(FunctionArgumentMetadata),
-      documentation: CodecArray.with(String)
+      name: Text,
+      arguments: Vector.with(FunctionArgumentMetadata),
+      documentation: Vector.with(Text)
     });
   }
 
-  get arguments (): CodecArray<FunctionArgumentMetadata> {
-    return this.raw.arguments as CodecArray<FunctionArgumentMetadata>;
+  get arguments (): Vector<FunctionArgumentMetadata> {
+    return this.raw.arguments as Vector<FunctionArgumentMetadata>;
   }
 
-  get documentation (): CodecArray<String> {
-    return this.raw.documentation as CodecArray<String>;
+  get documentation (): Vector<Text> {
+    return this.raw.documentation as Vector<Text>;
   }
 
   get id (): U16 {
     return this.raw.id as U16;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 }
 
-class CallMetadata extends CodecStruct {
+export class CallMetadata extends Struct {
   constructor () {
     super({
-      name: String,
-      functions: CodecArray.with(FunctionMetadata)
+      name: Text,
+      functions: Vector.with(FunctionMetadata)
     });
   }
 
-  get functions (): CodecArray<FunctionMetadata> {
-    return this.raw.functions as CodecArray<FunctionMetadata>;
+  get functions (): Vector<FunctionMetadata> {
+    return this.raw.functions as Vector<FunctionMetadata>;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 }
 
-class ModuleMetadata extends CodecStruct {
+export class ModuleMetadata extends Struct {
   constructor () {
     super({
-      name: String,
+      name: Text,
       call: CallMetadata
     });
   }
@@ -145,18 +145,18 @@ class ModuleMetadata extends CodecStruct {
     return this.raw.call as CallMetadata;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 }
 
-class StorageFunctionModifier extends CodecEnum {
+export class StorageFunctionModifier extends Enum {
   constructor () {
     super(['None', 'Default', 'Required']);
   }
 }
 
-class StorageFunctionType$Map extends CodecStruct {
+export class StorageFunctionType$Map extends Struct {
   constructor () {
     super({
       key: Type,
@@ -173,7 +173,7 @@ class StorageFunctionType$Map extends CodecStruct {
   }
 }
 
-class StorageFunctionType extends CodecEnumType<Type | StorageFunctionType$Map> {
+export class StorageFunctionType extends EnumType<Type | StorageFunctionType$Map> {
   constructor () {
     super([
       Type,
@@ -186,30 +186,30 @@ class StorageFunctionType extends CodecEnumType<Type | StorageFunctionType$Map>
   }
 
   get asMap (): StorageFunctionType$Map {
-    return (this.raw as CodecBase<StorageFunctionType$Map>).raw;
+    return (this.raw as Base<StorageFunctionType$Map>).raw;
   }
 
   get asType (): Type {
-    return (this.raw as CodecBase<Type>).raw;
+    return (this.raw as Base<Type>).raw;
   }
 }
 
-class StorageFunctionMetadata extends CodecStruct {
+export class StorageFunctionMetadata extends Struct {
   constructor () {
     super({
-      name: String,
+      name: Text,
       modifier: StorageFunctionModifier,
       type: StorageFunctionType,
-      documentation: CodecArray.with(String)
+      documentation: Vector.with(Text)
     });
   }
 
-  get documentation (): CodecArray<String> {
-    return this.raw.documentation as CodecArray<String>;
+  get documentation (): Vector<Text> {
+    return this.raw.documentation as Vector<Text>;
   }
 
-  get name (): String {
-    return this.raw.name as String;
+  get name (): Text {
+    return this.raw.name as Text;
   }
 
   get modifier (): StorageFunctionModifier {
@@ -221,29 +221,29 @@ class StorageFunctionMetadata extends CodecStruct {
   }
 }
 
-class StorageMetadata extends CodecStruct {
+export class StorageMetadata extends Struct {
   constructor () {
     super({
-      prefix: String,
-      functions: CodecArray.with(StorageFunctionMetadata)
+      prefix: Text,
+      functions: Vector.with(StorageFunctionMetadata)
     });
   }
 
-  get functions (): CodecArray<StorageFunctionMetadata> {
-    return this.raw.functions as CodecArray<StorageFunctionMetadata>;
+  get functions (): Vector<StorageFunctionMetadata> {
+    return this.raw.functions as Vector<StorageFunctionMetadata>;
   }
 
-  get prefix (): String {
-    return this.raw.prefix as String;
+  get prefix (): Text {
+    return this.raw.prefix as Text;
   }
 }
 
-class RuntimeModuleMetadata extends CodecStruct {
+export class RuntimeModuleMetadata extends Struct {
   constructor () {
     super({
-      prefix: String,
+      prefix: Text,
       module: ModuleMetadata,
-      storage: CodecOption.with(StorageMetadata)
+      storage: Option.with(StorageMetadata)
     });
   }
 
@@ -251,20 +251,20 @@ class RuntimeModuleMetadata extends CodecStruct {
     return this.raw.module as ModuleMetadata;
   }
 
-  get prefix (): String {
-    return this.raw.prefix as String;
+  get prefix (): Text {
+    return this.raw.prefix as Text;
   }
 
   get storage (): StorageMetadata | undefined {
-    return (this.raw.storage as CodecOption<StorageMetadata>).value;
+    return (this.raw.storage as Option<StorageMetadata>).value;
   }
 }
 
-export default class RuntimeMetadata extends CodecStruct {
+export default class RuntimeMetadata extends Struct {
   constructor (value?: any) {
     super({
       outerEvent: OuterEventMetadata,
-      modules: CodecArray.with(RuntimeModuleMetadata)
+      modules: Vector.with(RuntimeModuleMetadata)
     }, value);
   }
 
@@ -281,16 +281,16 @@ export default class RuntimeMetadata extends CodecStruct {
   }
 
   // FIXME Really not crazy about having to manually add all the getters. Preferably it should
-  // be done automagically in the actual CodecStruct - however what is really important here
+  // be done automagically in the actual Struct - however what is really important here
   // here is that we should nbot lose the autocompletion and checking that TS gives us. So if
   // we have to choose between the 2, manual defs it would have to be.
 
-  get events (): CodecArray<OuterEventMetadataEvent> {
+  get events (): Vector<OuterEventMetadataEvent> {
     return (this.raw.outerEvent as OuterEventMetadata).events;
   }
 
-  get modules (): CodecArray<RuntimeModuleMetadata> {
-    return this.raw.modules as CodecArray<RuntimeModuleMetadata>;
+  get modules (): Vector<RuntimeModuleMetadata> {
+    return this.raw.modules as Vector<RuntimeModuleMetadata>;
   }
 
   // Helper to retrieve a list of all type that are found, sorted and de-deuplicated
diff --git a/packages/api-codec/src/Index.ts b/packages/api-codec/src/Nonce.ts
similarity index 100%
rename from packages/api-codec/src/Index.ts
rename to packages/api-codec/src/Nonce.ts
diff --git a/packages/api-codec/src/PropIndex.ts b/packages/api-codec/src/PropIndex.ts
new file mode 100644
index 000000000000..072a6ac78d5a
--- /dev/null
+++ b/packages/api-codec/src/PropIndex.ts
@@ -0,0 +1,9 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import U32 from './U32';
+
+// An increasing number that represents a specific proposal in the system
+export default class PropIndex extends U32 {
+}
diff --git a/packages/api-codec/src/RawAddress.ts b/packages/api-codec/src/RawAddress.ts
new file mode 100644
index 000000000000..9c0650f9c910
--- /dev/null
+++ b/packages/api-codec/src/RawAddress.ts
@@ -0,0 +1,10 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import Address from './Address';
+
+// Wrapper for a RawAddress.
+// NOTE Not 100% on the differences between this and Address in the runtime
+export default class RawAddress extends Address {
+}
diff --git a/packages/api-codec/src/String.ts b/packages/api-codec/src/Text.ts
similarity index 88%
rename from packages/api-codec/src/String.ts
rename to packages/api-codec/src/Text.ts
index 3bae4651d169..118071b05b6c 100644
--- a/packages/api-codec/src/String.ts
+++ b/packages/api-codec/src/Text.ts
@@ -6,7 +6,7 @@ import u8aFromUtf8 from '@polkadot/util/u8a/fromUtf8';
 import u8aToUtf8 from '@polkadot/util/u8a/toUtf8';
 import u8aConcat from '@polkadot/util/u8a/concat';
 
-import CodecBase from './codec/Base';
+import Base from './codec/Base';
 import Length from './codec/Length';
 
 // This is a string wrapper, along with the length. It is used both for strings as well
@@ -17,14 +17,14 @@ import Length from './codec/Length';
 //   - Potentially we want a "TypeString" extension to this. Basically something that
 //     wraps the `Balance`, `T::AccountId`, etc. The reasoning - with a "TypeString"
 //     we can nicely strip types down like "T::AcountId" -> "AccountId"
-export default class String extends CodecBase<string> {
+export default class Text extends Base<string> {
   protected _length: Length;
 
-  constructor (value: String | string = '') {
+  constructor (value: Text | string = '') {
     super(
-      value instanceof String
+      value instanceof Text
         ? value.raw
-        : value
+        : value.trim()
     );
 
     this._length = new Length(value.length);
@@ -41,13 +41,13 @@ export default class String extends CodecBase<string> {
       this._length.byteLength();
   }
 
-  fromJSON (input: any): String {
+  fromJSON (input: any): Text {
     this.raw = `${input}`;
 
     return this;
   }
 
-  fromU8a (input: Uint8Array): String {
+  fromU8a (input: Uint8Array): Text {
     this._length.fromU8a(input);
 
     const length = this._length.toNumber();
diff --git a/packages/api-codec/src/Type.spec.js b/packages/api-codec/src/Type.spec.js
index f3bf369303b5..7d86ff5186c7 100644
--- a/packages/api-codec/src/Type.spec.js
+++ b/packages/api-codec/src/Type.spec.js
@@ -2,6 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
+import Text from './Text';
 import Type from './Type';
 
 describe('Type', () => {
@@ -17,15 +18,24 @@ describe('Type', () => {
     ).toEqual('Vec<AccountId>');
   });
 
-  it('handles aliasses, multiples per line', () => {
-    expect(
-      new Type().fromJSON('(PropIndex, AccountId, PropIndex)').toString()
-    ).toEqual('(ProposalIndex, AccountId, ProposalIndex)');
-  });
+  // currently no aliasses, code left as a comment, as here
+  // it('handles aliasses, multiples per line', () => {
+  //   expect(
+  //     new Type().fromJSON('(PropIndex, AccountId, PropIndex)').toString()
+  //   ).toEqual('(ProposalIndex, AccountId, ProposalIndex)');
+  // });
 
   it('does not allow toU8a', () => {
     expect(
       () => new Type().toU8a()
     ).toThrow(/unimplemented/);
   });
+
+  it('has a length for the type', () => {
+    expect(
+      new Type(
+        new Text(' Box<Proposal> ')
+      ).length
+    ).toEqual('Proposal'.length); // eslint-disable-line
+  });
 });
diff --git a/packages/api-codec/src/Type.ts b/packages/api-codec/src/Type.ts
index 446743950c65..0e088e05fcf1 100644
--- a/packages/api-codec/src/Type.ts
+++ b/packages/api-codec/src/Type.ts
@@ -2,14 +2,20 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import String from './String';
+import Text from './Text';
 
 type Mapper = (value: string) => string;
 
 // This is a extended version of String, specifically to handle types. Here we rely full on
 // what string provides us, however we also "tweak" the types received from the runtime, i.e.
 // we remove the `T::` prefixes found in some types for consistency accross implementation.
-export default class Type extends String {
+export default class Type extends Text {
+  constructor (value?: Text | string) {
+    super(value);
+
+    this._cleanupTypes();
+  }
+
   fromJSON (input: any): Type {
     super.fromJSON(input);
 
@@ -37,11 +43,7 @@ export default class Type extends String {
       // remove boxing, `Box<Proposal>` -> `Proposal`
       this._unwrap('Box<'),
       // remove generics, `MisbehaviorReport<Hash, BlockNumber>` -> `MisbehaviorReport`
-      this._ungeneric(),
-      // convert `RawAddress` -> `Address`
-      this._unalias('RawAddress', 'Address'),
-      // convert `PropIndex` -> `ProposalIndex`
-      this._unalias('PropIndex', 'ProposalIndex')
+      this._ungeneric()
     ];
 
     this.raw = mappings.reduce((result, fn) => {
@@ -70,15 +72,17 @@ export default class Type extends String {
     throw new Error(`Unable to find closing matching <> on '${value}' (start ${start})`);
   }
 
-  private _unalias (src: string, dest: string): Mapper {
-    return (value: string): string => {
-      while (value.indexOf(src) !== -1) {
-        value = value.replace(src, dest);
-      }
-
-      return value;
-    };
-  }
+  // convert `RawAddress` -> `Address`
+  // convert `PropIndex` -> `ProposalIndex`
+  // private _unalias (src: string, dest: string): Mapper {
+  //   return (value: string): string => {
+  //     while (value.indexOf(src) !== -1) {
+  //       value = value.replace(src, dest);
+  //     }
+
+  //     return value;
+  //   };
+  // }
 
   private _ungeneric (): Mapper {
     return (value: string): string => {
diff --git a/packages/api-codec/src/U128.ts b/packages/api-codec/src/U128.ts
index 3aec9a7cca99..3720ff935e10 100644
--- a/packages/api-codec/src/U128.ts
+++ b/packages/api-codec/src/U128.ts
@@ -4,10 +4,10 @@
 
 import BN from 'bn.js';
 
-import CodecNumber from './codec/Number';
+import UInt from './codec/UInt';
 
-export default class U128 extends CodecNumber {
-  constructor (value?: CodecNumber | BN | string | number) {
+export default class U128 extends UInt {
+  constructor (value?: UInt | BN | string | number) {
     super(value, 128);
   }
 }
diff --git a/packages/api-codec/src/U16.ts b/packages/api-codec/src/U16.ts
index 6c16910280e1..a64cbdf28715 100644
--- a/packages/api-codec/src/U16.ts
+++ b/packages/api-codec/src/U16.ts
@@ -4,10 +4,10 @@
 
 import BN from 'bn.js';
 
-import CodecNumber from './codec/Number';
+import UInt from './codec/UInt';
 
-export default class U16 extends CodecNumber {
-  constructor (value?: CodecNumber | BN | string | number) {
+export default class U16 extends UInt {
+  constructor (value?: UInt | BN | string | number) {
     super(value, 16);
   }
 }
diff --git a/packages/api-codec/src/U256.ts b/packages/api-codec/src/U256.ts
index bbe765a38785..6edcaefac973 100644
--- a/packages/api-codec/src/U256.ts
+++ b/packages/api-codec/src/U256.ts
@@ -4,10 +4,10 @@
 
 import BN from 'bn.js';
 
-import CodecNumber from './codec/Number';
+import UInt from './codec/UInt';
 
-export default class U256 extends CodecNumber {
-  constructor (value?: CodecNumber | BN | string | number) {
+export default class U256 extends UInt {
+  constructor (value?: UInt | BN | string | number) {
     super(value, 256);
   }
 }
diff --git a/packages/api-codec/src/U32.ts b/packages/api-codec/src/U32.ts
index 3b99f1eff99b..2f1453b1a23e 100644
--- a/packages/api-codec/src/U32.ts
+++ b/packages/api-codec/src/U32.ts
@@ -4,10 +4,10 @@
 
 import BN from 'bn.js';
 
-import CodecNumber from './codec/Number';
+import UInt from './codec/UInt';
 
-export default class U32 extends CodecNumber {
-  constructor (value?: CodecNumber | BN | string | number) {
+export default class U32 extends UInt {
+  constructor (value?: UInt | BN | string | number) {
     super(value, 32);
   }
 }
diff --git a/packages/api-codec/src/U64.ts b/packages/api-codec/src/U64.ts
index 08c1e9dca844..56770ca2f620 100644
--- a/packages/api-codec/src/U64.ts
+++ b/packages/api-codec/src/U64.ts
@@ -4,10 +4,10 @@
 
 import BN from 'bn.js';
 
-import CodecNumber from './codec/Number';
+import UInt from './codec/UInt';
 
-export default class U64 extends CodecNumber {
-  constructor (value?: CodecNumber | BN | string | number) {
+export default class U64 extends UInt {
+  constructor (value?: UInt | BN | string | number) {
     super(value, 64);
   }
 }
diff --git a/packages/api-codec/src/U8.ts b/packages/api-codec/src/U8.ts
index 7f21c6ab17ed..0860b5e4b6f4 100644
--- a/packages/api-codec/src/U8.ts
+++ b/packages/api-codec/src/U8.ts
@@ -4,10 +4,10 @@
 
 import BN from 'bn.js';
 
-import CodecNumber from './codec/Number';
+import UInt from './codec/UInt';
 
-export default class U8 extends CodecNumber {
-  constructor (value?: CodecNumber | BN | string | number) {
+export default class U8 extends UInt {
+  constructor (value?: UInt | BN | string | number) {
     super(value, 8);
   }
 }
diff --git a/packages/api-codec/src/codec/Base.ts b/packages/api-codec/src/codec/Base.ts
index 90a74c36af7d..ca20d028056c 100644
--- a/packages/api-codec/src/codec/Base.ts
+++ b/packages/api-codec/src/codec/Base.ts
@@ -8,7 +8,7 @@
 //
 // TODO
 //   - This could probably be abstract, as long as we have the functions abstract as well
-export default class CodecBase <T = any> {
+export default class Base <T = any> {
   raw: T;
 
   constructor (value?: any) {
@@ -16,26 +16,26 @@ export default class CodecBase <T = any> {
   }
 
   byteLength (): number {
-    throw new Error('CodecBase::byteLength: unimplemented');
+    throw new Error('Base::byteLength: unimplemented');
   }
 
-  fromJSON (input: any): CodecBase <T> {
-    throw new Error('CodecBase::fromJSON: unimplemented');
+  fromJSON (input: any): Base <T> {
+    throw new Error('Base::fromJSON: unimplemented');
   }
 
-  fromU8a (input: Uint8Array): CodecBase <T> {
-    throw new Error('CodecBase::fromU8a: unimplemented');
+  fromU8a (input: Uint8Array): Base <T> {
+    throw new Error('Base::fromU8a: unimplemented');
   }
 
   toJSON (): any {
-    throw new Error('CodecBase::toJSON: unimplemented');
+    throw new Error('Base::toJSON: unimplemented');
   }
 
   toString (): string {
-    throw new Error('CodecBase::toString: unimplemented');
+    throw new Error('Base::toString: unimplemented');
   }
 
   toU8a (): Uint8Array {
-    throw new Error('CodecBase::toU8a: unimplemented');
+    throw new Error('Base::toU8a: unimplemented');
   }
 }
diff --git a/packages/api-codec/src/codec/Bytes.ts b/packages/api-codec/src/codec/Bytes.ts
index 30103b44091a..1c51554b3fb4 100644
--- a/packages/api-codec/src/codec/Bytes.ts
+++ b/packages/api-codec/src/codec/Bytes.ts
@@ -4,31 +4,30 @@
 
 import u8aConcat from '@polkadot/util/u8a/concat';
 
-import CodecU8a from './U8a';
 import Length from './Length';
+import U8a from './U8a';
 
-// A CodecBytes. The significant difference between this and a normal Uint8Array is that
+// A Bytes. The significant difference between this and a normal Uint8Array is that
 // this version allows for length-encoding. (i.e. it is a variable-item codec, the same
 // as what is found in String and Array)
-export default class CodecBytes extends CodecU8a {
+export default class Bytes extends U8a {
   protected _length: Length;
 
-  constructor (value: CodecU8a | Uint8Array = new Uint8Array()) {
-    super(
-      value instanceof CodecU8a
-        ? value.raw
-        : value
-    );
+  constructor (value?: U8a | string | Uint8Array) {
+    super(value);
+
+    this._length = new Length(this.raw.length);
+  }
 
-    this._length = new Length(value.length);
+  get length (): number {
+    return this._length.toNumber();
   }
 
   byteLength (): number {
-    return this._length.byteLength() +
-      this._length.toNumber();
+    return this._length.byteLength() + this.length;
   }
 
-  fromJSON (input: any): CodecBytes {
+  fromJSON (input: any): Bytes {
     super.fromJSON(input);
 
     this._length.setValue(this.raw.length);
@@ -36,7 +35,7 @@ export default class CodecBytes extends CodecU8a {
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecBytes {
+  fromU8a (input: Uint8Array): Bytes {
     this._length.fromU8a(input);
 
     const length = this._length.toNumber();
diff --git a/packages/api-codec/src/codec/Enum.ts b/packages/api-codec/src/codec/Enum.ts
index 1bee0ea12f3a..03ed40350271 100644
--- a/packages/api-codec/src/codec/Enum.ts
+++ b/packages/api-codec/src/codec/Enum.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecBase from './Base';
+import Base from './Base';
 
 // A codec wrapper for an enum. Enums are encoded as a single byte, where the byte
 // is a zero-indexed value. This class allows you to retrieve the value either
@@ -11,7 +11,7 @@ import CodecBase from './Base';
 //
 // TODO:
 //   - It would be great if this could actually wrap actual TS enums
-export default class CodecEnum extends CodecBase<number> {
+export default class Enum extends Base<number> {
   private _strings: Array<string>;
 
   constructor (strings: Array<string>, value: number = 0) {
@@ -24,13 +24,13 @@ export default class CodecEnum extends CodecBase<number> {
     return 1;
   }
 
-  fromJSON (input: any): CodecEnum {
+  fromJSON (input: any): Enum {
     this.raw = input;
 
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecEnum {
+  fromU8a (input: Uint8Array): Enum {
     this.raw = input[0];
 
     return this;
diff --git a/packages/api-codec/src/codec/EnumType.ts b/packages/api-codec/src/codec/EnumType.ts
index 48bd13586fda..9b5d49c53010 100644
--- a/packages/api-codec/src/codec/EnumType.ts
+++ b/packages/api-codec/src/codec/EnumType.ts
@@ -2,7 +2,7 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecBase from './Base';
+import Base from './Base';
 
 // This implements an enum, that based on the value wraps a different type. It is effectively an
 // extension to enum where the value type is determined by the actual index.
@@ -11,12 +11,12 @@ import CodecBase from './Base';
 //   - As per Enum, actually use TS enum
 //   - It should rather probably extend Enum instead of copying code
 //   - There doesn't actually seem to be a way to get to the actual determined/wrapped value
-export default class CodecEnumType <T> extends CodecBase<CodecBase<T>> {
-  private _Type: Array<{ new(value?: any): CodecBase }>;
+export default class EnumType <T> extends Base<Base<T>> {
+  private _Type: Array<{ new(value?: any): Base }>;
   private _index: number;
   private _strings: Array<string>;
 
-  constructor (Type: Array<{ new(value?: any): CodecBase }>, strings: Array<string>, index: number = 0) {
+  constructor (Type: Array<{ new(value?: any): Base }>, strings: Array<string>, index: number = 0) {
     super(
       new Type[index]()
     );
@@ -30,11 +30,11 @@ export default class CodecEnumType <T> extends CodecBase<CodecBase<T>> {
     return 1 + this.raw.byteLength();
   }
 
-  fromJSON (input: any): CodecEnumType<T> {
-    throw new Error('CodecEnumType:fromJSON: unimplemented');
+  fromJSON (input: any): EnumType<T> {
+    throw new Error('EnumType:fromJSON: unimplemented');
   }
 
-  fromU8a (input: Uint8Array): CodecEnumType<T> {
+  fromU8a (input: Uint8Array): EnumType<T> {
     this._index = input[0];
     this.raw = new this._Type[this._index]().fromU8a(input.subarray(1));
 
@@ -46,7 +46,7 @@ export default class CodecEnumType <T> extends CodecBase<CodecBase<T>> {
   }
 
   toU8a (): Uint8Array {
-    throw new Error('CodecEnumType:toU8a: unimplemented');
+    throw new Error('EnumType:toU8a: unimplemented');
   }
 
   toNumber (): number {
diff --git a/packages/api-codec/src/codec/Length.spec.js b/packages/api-codec/src/codec/Length.spec.js
index c2abeaeca01a..6dc0e134f7ad 100644
--- a/packages/api-codec/src/codec/Length.spec.js
+++ b/packages/api-codec/src/codec/Length.spec.js
@@ -4,7 +4,7 @@
 
 import Length from './Length';
 
-describe('Compact', () => {
+describe('Length', () => {
   it('encodes short u8', () => {
     expect(
       new Length(18).toU8a()
@@ -29,14 +29,18 @@ describe('Compact', () => {
     );
   });
 
+  it('encodes basic ua6 (not at edge)', () => {
+    expect(
+      new Length(111).toHex()
+    ).toEqual('0xbd01');
+  });
+
   it('decodes from same u16 encoded value', () => {
     expect(
       new Length()
         .fromU8a(new Uint8Array([0b11111101, 0b00000111]))
         .toNumber()
-    ).toEqual(
-      511
-    );
+    ).toEqual(511);
   });
 
   it('encodes basic u32 values (short)', () => {
@@ -52,9 +56,7 @@ describe('Compact', () => {
       new Length()
         .fromU8a(new Uint8Array([254, 255, 3, 0]))
         .toNumber()
-    ).toEqual(
-      0xffff
-    );
+    ).toEqual(0xffff);
   });
 
   it('encodes basic u32 values (full)', () => {
@@ -70,8 +72,6 @@ describe('Compact', () => {
       new Length()
         .fromU8a(new Uint8Array([3, 249, 255, 255, 255]))
         .toNumber()
-    ).toEqual(
-      0xfffffff9
-    );
+    ).toEqual(0xfffffff9);
   });
 });
diff --git a/packages/api-codec/src/codec/Length.ts b/packages/api-codec/src/codec/Length.ts
index 36ea20067853..5fad109c3d66 100644
--- a/packages/api-codec/src/codec/Length.ts
+++ b/packages/api-codec/src/codec/Length.ts
@@ -7,8 +7,9 @@ import bnToBn from '@polkadot/util/bn/toBn';
 import bnToU8a from '@polkadot/util/bn/toU8a';
 import u8aConcat from '@polkadot/util/u8a/concat';
 import u8aToBn from '@polkadot/util/u8a/toBn';
+import u8aToHex from '@polkadot/util/u8a/toHex';
 
-import CodecBase from './Base';
+import Base from './Base';
 
 const MAX_U8 = new BN(2).pow(new BN(8 - 2)).subn(1);
 const MAX_U16 = new BN(2).pow(new BN(16 - 2)).subn(1);
@@ -29,10 +30,10 @@ const MAX_U32 = new BN(2).pow(new BN(32 - 2)).subn(1);
 //     nn nn nn 11 [ / zz zz zz zz ]{4 + n}
 //
 // Note: we use *LOW BITS* of the LSB in LE encoding to encode the 2 bit key.
-export default class CodecLength extends CodecBase<BN> {
-  constructor (value: CodecLength | BN | number = new BN(0)) {
+export default class Length extends Base<BN> {
+  constructor (value: Length | BN | number = new BN(0)) {
     super(
-      value instanceof CodecLength
+      value instanceof Length
         ? value.raw
         : bnToBn(value)
     );
@@ -69,32 +70,32 @@ export default class CodecLength extends CodecBase<BN> {
     );
   }
 
-  get length (): number {
-    return this.raw.toNumber();
-  }
-
   byteLength (): number {
     return this.toU8a().length;
   }
 
-  fromJSON (): CodecLength {
-    throw new Error('CodecLength::fromJSON: unimplemented');
+  fromJSON (): Length {
+    throw new Error('Length::fromJSON: unimplemented');
   }
 
-  fromNumber (value: BN | number): CodecLength {
+  fromNumber (value: BN | number): Length {
     this.raw = bnToBn(value);
 
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecLength {
-    this.raw = CodecLength.decode(input);
+  fromU8a (input: Uint8Array): Length {
+    this.raw = Length.decode(input);
 
     return this;
   }
 
   toJSON (): any {
-    throw new Error('CodecLength::toJSON: unimplemented');
+    throw new Error('Length::toJSON: unimplemented');
+  }
+
+  toHex (): string {
+    return u8aToHex(this.toU8a());
   }
 
   toNumber (): number {
@@ -102,11 +103,11 @@ export default class CodecLength extends CodecBase<BN> {
   }
 
   toString (): string {
-    throw new Error('CodecLength::toString: unimplemented');
+    throw new Error('Length::toString: unimplemented');
   }
 
   toU8a (): Uint8Array {
-    return CodecLength.encode(this.raw);
+    return Length.encode(this.raw);
   }
 
   setValue (value: BN | number): void {
diff --git a/packages/api-codec/src/codec/Option.ts b/packages/api-codec/src/codec/Option.ts
index 1cbb8244f715..59b0255d05f7 100644
--- a/packages/api-codec/src/codec/Option.ts
+++ b/packages/api-codec/src/codec/Option.ts
@@ -4,16 +4,16 @@
 
 import isUndefined from '@polkadot/util/is/undefined';
 
-import CodecBase from './Base';
+import Base from './Base';
 
 // An Option is an optional field. Basically the first byte indicates that there is
-// is value to follow. If the byte is `1` there is an actual value. So the CodecOption
+// is value to follow. If the byte is `1` there is an actual value. So the Option
 // implements that - decodes, checks for optionality and wraps the required structure
 // with a value if/as required/found.
-export default class CodecOption <T> extends CodecBase<CodecBase<T>> {
+export default class Option <T> extends Base<Base<T>> {
   private _hasValue: boolean;
 
-  constructor (Value: { new(value?: any): CodecBase<T> }, value?: any) {
+  constructor (Value: { new(value?: any): Base<T> }, value?: any) {
     super(
       new Value(value)
     );
@@ -21,8 +21,8 @@ export default class CodecOption <T> extends CodecBase<CodecBase<T>> {
     this._hasValue = !isUndefined(value);
   }
 
-  static with <O> (Type: { new(value?: any): CodecBase<O> }): { new(value?: any): CodecOption<O> } {
-    return class extends CodecOption<O> {
+  static with <O> (Type: { new(value?: any): Base<O> }): { new(value?: any): Option<O> } {
+    return class extends Option<O> {
       constructor (value?: any) {
         super(Type, value);
       }
@@ -43,7 +43,7 @@ export default class CodecOption <T> extends CodecBase<CodecBase<T>> {
     return 1 + childLength;
   }
 
-  fromJSON (input: any): CodecOption<T> {
+  fromJSON (input: any): Option<T> {
     this._hasValue = !isUndefined(input);
 
     if (this._hasValue) {
@@ -53,7 +53,7 @@ export default class CodecOption <T> extends CodecBase<CodecBase<T>> {
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecOption<T> {
+  fromU8a (input: Uint8Array): Option<T> {
     this._hasValue = input[0] === 1;
 
     if (this._hasValue) {
diff --git a/packages/api-codec/src/codec/Struct.ts b/packages/api-codec/src/codec/Struct.ts
index 3929afbe7bc2..95063cc24abc 100644
--- a/packages/api-codec/src/codec/Struct.ts
+++ b/packages/api-codec/src/codec/Struct.ts
@@ -4,29 +4,29 @@
 
 import u8aConcat from '@polkadot/util/u8a/concat';
 
-import CodecBase from './Base';
+import Base from './Base';
 
-// A Struct defines an Object with key/values - where the values are CodecCodecBase values. It removes
-// a lot of repetition from the actual coding, define a structure type, pass it the key/CodecBase<T>
+// A Struct defines an Object with key/values - where the values are CodecBase values. It removes
+// a lot of repetition from the actual coding, define a structure type, pass it the key/Base<T>
 // values in the constructor and it manages the decoding. It is important that the constructor
 // values matches 100% to the order in th Rust code, i.e. don't go crazy and make it alphabetical,
 // it needs to decoded in the specific defined order.
 //
 // TODO:
 //   - Check the constructor, something is really, really wrong with the way the defs are used
-export default class CodecStruct <
-  S = { [index: string]: { new(value?: any): CodecBase } },
-  T = { [K in keyof S]: CodecBase },
+export default class Struct <
+  S = { [index: string]: { new(value?: any): Base } },
+  T = { [K in keyof S]: Base },
   V = { [K in keyof S]: any }
-> extends CodecBase<T> {
-  constructor (Struct: S, value: V = {} as V) {
+> extends Base<T> {
+  constructor (Def: S, value: V = {} as V) {
     super(
-      Object.keys(Struct).reduce((raw: T, key) => {
+      Object.keys(Def).reduce((raw: T, key) => {
         // @ts-ignore Ok, something weid is going on here or I just don't get it... it works,
         // so ignore the checker, although it drives me batty. (It started when the [key in keyof T]
         // was added, the idea is to provide better checks, which does backfire here, but works
         // externally.)
-        raw[key] = new Struct[key](value[key]);
+        raw[key] = new Def[key](value[key]);
 
         return raw;
       }, {} as T)
@@ -34,11 +34,11 @@ export default class CodecStruct <
   }
 
   static with <
-    S = { [index: string]: { new(value?: any): CodecBase } }
-  > (Struct: S): { new(value?: any): CodecStruct<S> } {
-    return class extends CodecStruct<S> {
+    S = { [index: string]: { new(value?: any): Base } }
+  > (Def: S): { new(value?: any): Struct<S> } {
+    return class extends Struct<S> {
       constructor (value?: any) {
-        super(Struct, value);
+        super(Def, value);
       }
     };
   }
@@ -49,7 +49,7 @@ export default class CodecStruct <
     }, 0);
   }
 
-  fromJSON (input: any): CodecStruct<S, T, V> {
+  fromJSON (input: any): Struct<S, T, V> {
     Object.keys(this.raw).forEach((key) => {
       // @ts-ignore as above...
       this.raw[key].fromJSON(input[key]);
@@ -58,7 +58,7 @@ export default class CodecStruct <
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecStruct<S, T, V> {
+  fromU8a (input: Uint8Array): Struct<S, T, V> {
     Object.keys(this.raw).reduce((offset, key) => {
       // @ts-ignore as above...
       this.raw[key].fromU8a(input.subarray(offset));
diff --git a/packages/api-codec/src/codec/U8a.spec.js b/packages/api-codec/src/codec/U8a.spec.js
new file mode 100644
index 000000000000..bc5902de2202
--- /dev/null
+++ b/packages/api-codec/src/codec/U8a.spec.js
@@ -0,0 +1,23 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import U8a from './U8a';
+
+describe('U8a', () => {
+  let u8a;
+
+  beforeEach(() => {
+    u8a = new U8a([1, 2, 3, 4, 5]);
+  });
+
+  it('contains the length of the elements', () => {
+    expect(u8a.length).toEqual(5); // eslint-disable-line
+  });
+
+  it('allows wrapping of a pre-existing instance', () => {
+    expect(
+      new U8a(u8a).length
+    ).toEqual(5); // eslint-disable-line
+  });
+});
diff --git a/packages/api-codec/src/codec/U8a.ts b/packages/api-codec/src/codec/U8a.ts
index dae202090429..b44ea6530da3 100644
--- a/packages/api-codec/src/codec/U8a.ts
+++ b/packages/api-codec/src/codec/U8a.ts
@@ -5,16 +5,16 @@
 import u8aToHex from '@polkadot/util/u8a/toHex';
 import toU8a from '@polkadot/util/u8a/toU8a';
 
-import CodecBase from './Base';
+import Base from './Base';
 
-// A CodecU8a. A basic wrapper around Uint8Array, with no frills and no fuss. It
+// A U8a. A basic wrapper around Uint8Array, with no frills and no fuss. It
 // wraps a Uint8Array. It does differ from other implementations wher it will
 // consume the full u8a as passed to it in fromU8a. As such it is meant to be
 // subclassed where the wrapper takes care of the actual lengths.
-export default class CodecU8a extends CodecBase<Uint8Array> {
-  constructor (value: CodecU8a | string | Uint8Array = new Uint8Array()) {
+export default class U8a extends Base<Uint8Array> {
+  constructor (value: U8a | string | Uint8Array | Array<number> = new Uint8Array()) {
     super(
-      value instanceof CodecU8a
+      value instanceof U8a
         ? value.raw
         : toU8a(value)
     );
@@ -28,13 +28,13 @@ export default class CodecU8a extends CodecBase<Uint8Array> {
     return this.raw.length;
   }
 
-  fromJSON (input: any): CodecU8a {
+  fromJSON (input: any): U8a {
     this.raw = toU8a(input);
 
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecU8a {
+  fromU8a (input: Uint8Array): U8a {
     this.raw = input;
 
     return this;
diff --git a/packages/api-codec/src/codec/U8aFixed.spec.js b/packages/api-codec/src/codec/U8aFixed.spec.js
new file mode 100644
index 000000000000..3d194f32357c
--- /dev/null
+++ b/packages/api-codec/src/codec/U8aFixed.spec.js
@@ -0,0 +1,29 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import U8aFixed from './U8aFixed';
+
+describe('U8aFixed', () => {
+  let u8a;
+
+  beforeEach(() => {
+    u8a = new U8aFixed([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 32);
+  });
+
+  it('limits the length', () => {
+    expect(u8a.length).toEqual(4); // eslint-disable-line
+  });
+
+  it('allows wrapping of a pre-existing instance', () => {
+    expect(
+      u8a.toU8a()
+    ).toEqual(new Uint8Array([1, 2, 3, 4]));
+  });
+
+  it('allows empty values', () => {
+    expect(
+      new U8aFixed().toHex()
+    ).toEqual('0x');
+  });
+});
diff --git a/packages/api-codec/src/codec/U8aFixed.ts b/packages/api-codec/src/codec/U8aFixed.ts
index b8fe459ad989..78a83b8859fe 100644
--- a/packages/api-codec/src/codec/U8aFixed.ts
+++ b/packages/api-codec/src/codec/U8aFixed.ts
@@ -2,26 +2,40 @@
 // This software may be modified and distributed under the terms
 // of the ISC license. See the LICENSE file for details.
 
-import CodecU8a from './U8a';
+import U8a from './U8a';
 
 type BitLength = 256 | 512;
 
 // A U8a that manages a a sequence of bytes up to the specified bitLength. Not meant
 // to be used directly, rather is should be subclassed with the specific lengths.
-export default class CodecU8aFixed extends CodecU8a {
+export default class U8aFixed extends U8a {
   protected _bitLength: number;
 
-  constructor (value: CodecU8a | string | Uint8Array = new Uint8Array(), bitLength: BitLength = 256) {
+  constructor (value: U8a | string | Uint8Array = new Uint8Array(), bitLength: BitLength = 256) {
     super(value);
 
     this._bitLength = bitLength;
+
+    this._trimLength();
+  }
+
+  private _trimLength (): void {
+    this.raw = this.raw.subarray(0, this.byteLength());
   }
 
   byteLength (): number {
     return this._bitLength / 8;
   }
 
-  fromU8a (input: Uint8Array): CodecU8aFixed {
+  fromJSON (input: any): U8aFixed {
+    super.fromJSON(input);
+
+    this._trimLength();
+
+    return this;
+  }
+
+  fromU8a (input: Uint8Array): U8aFixed {
     super.fromU8a(input.subarray(0, this.byteLength()));
 
     return this;
diff --git a/packages/api-codec/src/codec/Number.ts b/packages/api-codec/src/codec/UInt.ts
similarity index 79%
rename from packages/api-codec/src/codec/Number.ts
rename to packages/api-codec/src/codec/UInt.ts
index 78c66271c0cf..06de236be28e 100644
--- a/packages/api-codec/src/codec/Number.ts
+++ b/packages/api-codec/src/codec/UInt.ts
@@ -11,7 +11,7 @@ import bnToU8a from '@polkadot/util/bn/toU8a';
 import hexToBn from '@polkadot/util/hex/toBn';
 import u8aToBn from '@polkadot/util/u8a/toBn';
 
-import CodecBase from './Base';
+import Base from './Base';
 
 type BitLength = 8 | 16 | 32 | 64 | 128 | 256;
 
@@ -21,19 +21,19 @@ type BitLength = 8 | 16 | 32 | 64 | 128 | 256;
 //
 // TODO:
 //   - Apart from encoding/decoding we don't actuall keep check on the sizes, is this good enough?
-export default class CodecNumber extends CodecBase<BN> {
+export default class UInt extends Base<BN> {
   private _bitLength: BitLength;
 
-  constructor (value: CodecNumber | BN | string | number = 0, bitLength: BitLength = 64) {
+  constructor (value: UInt | BN | string | number = 0, bitLength: BitLength = 64) {
     super(
-      CodecNumber.decode(value)
+      UInt.decode(value)
     );
 
     this._bitLength = bitLength;
   }
 
-  static decode (value: CodecNumber | BN | string | number): BN {
-    if (value instanceof CodecNumber) {
+  static decode (value: UInt | BN | string | number): BN {
+    if (value instanceof UInt) {
       return value.raw;
     } else if (isHex(value)) {
       return hexToBn(value as string);
@@ -48,13 +48,13 @@ export default class CodecNumber extends CodecBase<BN> {
     return this._bitLength / 8;
   }
 
-  fromJSON (input: any): CodecNumber {
-    this.raw = CodecNumber.decode(input);
+  fromJSON (input: any): UInt {
+    this.raw = UInt.decode(input);
 
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecNumber {
+  fromU8a (input: Uint8Array): UInt {
     this.raw = u8aToBn(input.subarray(0, this.byteLength()), true);
 
     return this;
diff --git a/packages/api-codec/src/codec/Vector.spec.js b/packages/api-codec/src/codec/Vector.spec.js
new file mode 100644
index 000000000000..b43671653992
--- /dev/null
+++ b/packages/api-codec/src/codec/Vector.spec.js
@@ -0,0 +1,81 @@
+// Copyright 2017-2018 @polkadot/api-codec authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import Text from '../Text';
+import Vector from './Vector';
+
+describe('Vector', () => {
+  let array;
+
+  beforeEach(() => {
+    array = new Vector(Text, [ '1', '23', '345', '4567', new Text('56789') ]);
+  });
+
+  it('wraps a sequence of values', () => {
+    expect(array.length).toEqual(5); // eslint-disable-line
+  });
+
+  it('has a sane representation for toString', () => {
+    expect(array.toString()).toEqual('[1, 23, 345, 4567, 56789]');
+  });
+
+  it('encodes with length prefix', () => {
+    expect(array.toU8a()).toEqual(new Uint8Array([
+      5 << 2,
+      1 << 2, 49,
+      2 << 2, 50, 51,
+      3 << 2, 51, 52, 53,
+      4 << 2, 52, 53, 54, 55,
+      5 << 2, 53, 54, 55, 56, 57
+    ]));
+  });
+
+  it('allows contruction via JSON', () => {
+    expect(
+      new Vector(Text).fromJSON(['6', '7']).toString()
+    ).toEqual('[6, 7]');
+  });
+
+  describe('array-like functions', () => {
+    it('allows retrieval of a specific item', () => {
+      expect(
+        array.at(2).toString()
+      ).toEqual('345');
+    });
+
+    it('exposes a working forEach', () => {
+      const result = {};
+
+      array.forEach((e, i) => {
+        result[i] = e.toString();
+      });
+
+      expect(result).toEqual({
+        0: '1',
+        1: '23',
+        2: '345',
+        3: '4567',
+        4: '56789'
+      });
+    });
+
+    it('exposes a working filter', () => {
+      expect(
+        array.filter((e, i) => i >= 3).toString()
+      ).toEqual('4567,56789');
+    });
+
+    it('exposes a working map', () => {
+      expect(
+        array.map((e) => e.toString().substr(0, 1))
+      ).toEqual(['1', '2', '3', '4', '5']);
+    });
+
+    it('exposes a working reduce', () => {
+      expect(
+        array.reduce((r, e) => `${r}${e}`, '')
+      ).toEqual('123345456756789');
+    });
+  });
+});
diff --git a/packages/api-codec/src/codec/Array.ts b/packages/api-codec/src/codec/Vector.ts
similarity index 85%
rename from packages/api-codec/src/codec/Array.ts
rename to packages/api-codec/src/codec/Vector.ts
index 9ab23a684d53..d977beb3c84c 100644
--- a/packages/api-codec/src/codec/Array.ts
+++ b/packages/api-codec/src/codec/Vector.ts
@@ -4,7 +4,7 @@
 
 import u8aConcat from '@polkadot/util/u8a/concat';
 
-import CodecBase from './Base';
+import Base from './Base';
 import Length from './Length';
 
 // This manages codec arrays. Intrernally it keeps track of the length (as decoded) and allows
@@ -12,16 +12,18 @@ import Length from './Length';
 // i.e. while it wraps an array, it provides a `length` property to get the actual length, `at(index)`
 // to retrieve a specific item. Additionally the helper functions `map`, `filter`, `forEach` and
 // `reduce` is exposed on the interface.
-export default class CodecArray <
-  T extends CodecBase
-> extends CodecBase<Array<T>> {
+export default class Vector <
+  T extends Base
+> extends Base<Array<T>> {
   private _length: Length;
   private _Type: { new(value?: any): T };
 
   constructor (Type: { new(value?: any): T }, value: Array<any> = [] as Array<any>) {
     super(
       value.map((entry) =>
-        new Type(entry)
+        entry instanceof Type
+          ? entry
+          : new Type(entry)
       )
     );
 
@@ -29,8 +31,8 @@ export default class CodecArray <
     this._Type = Type;
   }
 
-  static with <O extends CodecBase> (Type: { new(value?: any): O }): { new(value?: any): CodecArray<O> } {
-    return class extends CodecArray<O> {
+  static with <O extends Base> (Type: { new(value?: any): O }): { new(value?: any): Vector<O> } {
+    return class extends Vector<O> {
       constructor (value?: Array<any>) {
         super(Type, value);
       }
@@ -59,7 +61,7 @@ export default class CodecArray <
     return this.raw.forEach(fn);
   }
 
-  fromJSON (input: any): CodecArray<T> {
+  fromJSON (input: any): Vector<T> {
     this.raw = input.map((input: any) =>
       new this._Type().fromJSON(input)
     );
@@ -67,7 +69,7 @@ export default class CodecArray <
     return this;
   }
 
-  fromU8a (input: Uint8Array): CodecArray<T> {
+  fromU8a (input: Uint8Array): Vector<T> {
     this._length.fromU8a(input);
 
     const length = this._length.toNumber();
@@ -110,8 +112,8 @@ export default class CodecArray <
   toString (): string {
     const data = this.raw.map((entry) =>
       entry.toString()
-    ).join(', ');
+    );
 
-    return `[${data}]`;
+    return `[${data.join(', ')}]`;
   }
 }