1. No batteries, clockwork drive, easy to use, similar to the operation of quartz clocks 2. Divided into two movements, left and right, each fully wound can continue to go not less than 36 hours, time accuracy of about 3 minutes a day error 3. Material: plastic shell, zinc alloy movement 4. Maintenance: chess clock should be prevented from contact with corrosive substances, avoid exposure to the sun, rain, drops and close to strong magnetic fields 5. Size: about 15 x 5.5 x 9cm 6. Weight: about 290g Use method: 1. Place the chess clock on a flat table before use 2. Wind up the clock in the direction of the arrow on the back cover, and don't rotate it hard after winding up to avoid damage. 3. Dial the hands: first dial the minute hand in the 12 position, but also according to the need to dial the minute hand in any indicator position. When dialing the hands must be dialed in the vertical position of the clock, so as to avoid the minute hand stuck in the indicator flag caused by the displacement of the minute hand 4. start: press the left button, the left clock stop the right clock start, press the right button, the right clock stop the left clock start (but should not hit the button, so as not to cause damage) 5. Fast and slow adjustment: If there is a fast and slow error, you should use a small metal rod to adjust the fast and slow mechanism in the direction of the back cover moon hole.Items from YU wen's store