These contracts make parent chain block hashes available to Arbitrum chains.
There are two contracts: the Pusher and Buffer. The Pusher exists on each parent chain, allowing callers to send block hashes up to a Buffer contract on any child chain.
Both contracts are deployed via the CREATE2 factory at 0x4e59b44847b379578588920cA78FbF26c0B4956C using the salt 0xeb44f642e5f5e0fa3d1a50c1ffbb26f929a86ade59a78f8ef4968dc9b88d15a0, resulting in the following contract addresses on all chains:
Buffer:0x0000000048C4Ed10cF14A02B9E0AbDDA5227b071Pusher:0x5a5C4f3D0F0Efaeed2aEc9B59B67eC62a4666D88