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 1 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 shell features a unique molding process that allows the clock to be positioned at a slight angle for better visibility, reducing glare and improving screen readability. Usage 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 manually set the hour and minute hands to 12 o'clock. For timing purposes, align the "small red flag" indicator to the upper right 12 o'clock position, using its free-fall moment as the reference for zero alignment. Color: Black Material: Plastic Size: 18 x 6.5 x 11.5 cm Package Contents: 1 x Chess Clock Note: AA battery not included. Package includes only the items listed. Due to lighting and display differences, the actual color may vary slightly from the image. Measurement error allowed is +/- 1-3 cm.