Description: A. 0.56 inch special red digital clock display; B. Import AT89C2051 into the master chip; C.1.2mm thick PCB made of military grade FR-4 board; Re. Accurate travel time, travel time error range error -1 to +1 seconds every 24 hours. Specification: AT89C2051-based four electronic clock set Model set: YSZ-4 Supply voltage: 3V-6V Board size: 52mm * width 42mm Function: 1. Seconds correction (for accurate school) 2. Switch to each minute of individual display interface 3 .The whole point of time (8-20 o\' clock chime can be turned off) 4. Two alarm settings (you can turn off the alarm function) Package includes: 1 x electronic clock module (unassembled) Note: 1. This product is DIY kits, not final product! We do not provide technical support please make sure you are familiar with the product before purchasing. 2. The real color of the item may be slightly different from the pictures shown on website caused by many factors such as brightness of your monitor and light brightness. 3. Please allow slight manual measurement deviation for the data.