Features:

• 24h mode
• easy assembly
• arduino compatible firmware ATMEGA328 or another runing on internal RC oscillator (no crystal needed )
• ultra high precise time with RTC DS3231 onboard or RTC module
• CR2032 battery backup
• separated HV power supply (not included, you can connect any HV module) etc. specially THIS ONE from ebay fit prefect.
• beautiful white single board
• readable clean design
• cathode poisoning prevention
• 3mm holes under nixies for optional back-light
• optional DS18B20 sensor
• dimensions 15cm x 10cm