The board 25MHZ crystal
arduino
Gikfun 6 Bits Digital LED Electronic Clock DIY Kits PCB Soldering Practice Learning Board AT89C2051 FR-4 for Arduino EK1323
It is programmed AT89C2051 MCU chip, precise time display, 24 hours format, supporting seconds correction, countdown clock, stopwatch, counter, hourly chime and alarm clock functions.