The main rules: dry system, plus seconds system, time limit system, read the system, every move fast chess, positive timing Sound switch: can be set to mute, can be turned off, the back of the set rules: simple and convenient Size: 19cm x 13cm x 3.5cm Color: Black Material: ABS Power supply mode: 2 AAA batteries (not included) Package Contents: 1 x Chess Clock Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.