Game Clock: This clock features a mechanical structure with a timing start button. It is simple to operate: press the left button, the left timer stops and the right timer starts. Press the right button, the right timer stops and the left timer starts. Pressing both buttons halfway simultaneously stops both timers. Practical Clock: The PQ9905 quartz analog chess clock is suitable for chess and Chinese chess. Accurate Timing: Provides precise timing with less than one second error, ideal for various chess games. Lightweight and Durable: Made with a sturdy plastic shell, lightweight and easy to carry, suitable for both recreational and competitive use. Ergonomic Design: The unique molding process allows the clock to be positioned at a slight angle for better visibility, reducing glare and improving screen readability. Instructions: 1) Timing button operation: Press the left button to stop the left timer and start the right timer. Press the right button to stop the right timer and start the left timer. Press both buttons halfway at the same time to stop both timers. 2) Second hand zero adjustment: Alternate pressing both buttons to adjust each second hand to the 12 o'clock position (zero). Use the adjustment hole on the back of the clock to set the hour and minute hands to 12 o'clock. For the second hand zero position, align the small red flag indicator to the upper right 12 o'clock position, allowing the flag to drop freely to confirm correct alignment. Color: Black Material: Plastic Size: 18 x 6.5 x 11.5 cm Package Contents: 1 x Chess Clock Note: One AA battery is not included. The package includes only the items listed above. Note: Lighting and display differences may cause slight variations in color between the image and the actual item. Measurement error is +/- 1-3 cm.