1. No battery needed, clockwork drive, easy to use, similar to quartz clock operation 2. Divided into left and right movements, each full spring can last for no less than 36 hours, and the daily error of travel time accuracy is about 3 minutes 3. Material: plastic case, zinc alloy movement 4. Maintenance: The chess clock should be protected from contact with corrosive substances, avoid exposure to sunlight, rain, drop and close to strong magnetic fields 5. Size: about 15x5.5x9cm 6. Weight: about 280 grams Instructions: 1. Place the chess clock on a flat table before use 2. Press the direction indicated by the arrow on the back cover to fully wind up the mainspring. After the mainspring is wound up, do not twist it hard to avoid damage. 3. Set the needle: first set the minute hand to the 12th position, or set the minute hand to any indicated position as needed. When dialing the hand, be sure to turn the clock in a vertical position to avoid the minute hand being stuck on the indicator flag and causing the minute hand to shift. 4. Start: Press the left button, the left clock stops and the right clock starts to start, press the right button, the right clock stops and the left clock starts to start (but it is not advisable to hit the button hard to avoid damage) 5. Speed adjustment: If there is a speed error, you should use a small metal rod to adjust the speed mechanism in the hole in the direction pointed to the left and right of the moon-shaped hole in the back cover