Mvpower&reg;C51 4 Bits Digital AT89C2051 Electronic Clock Electronic Clocks Production Suit Set DIY Kits 3V-6V New AT89C2051-based of four electronic clock kit Supply voltage: 3V-6V PCB Size: 52mm * wide 42mm Function: 1. Seconds correction (for precise School) 2. Switch to every minute independent display interface 3. whole point of time (8-20 o'clock chime can be turned off) 4. Two alarm settings (you can turn off the alarm function) Kit Features: A. 0.56 inch special red digital clock for display; B. Import AT89C2051 for master chip; C.1.2mm thick PCB made from military grade FR-4 board; D. accurate travel time, travel time error range error -1 to +1 seconds every 24 hours.