Operating voltage: 5-12V                                      Features: alarm clock, stopwatch, countdown and counter.                                      Instructions for use:                                                    1. Function button description: S1 is the function selection button, S2 is the function expansion button, and S3 is the value plus one button.                                                    2. Function and operation instructions: During operation, press S1 for a short time (less than 1 second) continuously to cycle through the above 6 functions. If you press and hold S1 for a long time (more than 2 seconds) in the middle, it will immediately return to the state of the clock function.                                                    ①Clock function: It will display 10:10:00 after power on, which means perfect.                                                    ② Timing function: short press S1 once, that is, the current time is flashing, press S2, the hour digit will increase by 1, and if you press S3, the minute digit will increase by 1, and the second time cannot be adjusted.                                                    ③Alarm clock function: short press S1 twice, the display state is 22:10:00, and the colon is long on. Press S2 to add 1 to the hour, and press S3 to add 1 to the minute. The second is not adjustable. When the hour digit exceeds 23, it will display --:--:--, which means to turn off the alarm clock function. The alarm sound is the buzzer beeping for 3 seconds.                                                    ④Countdown function: short press S1 three times, the display status is 0. Press S2 to display the high position from the low position, and press S3 to increase the corresponding position by 1. When S2 is pressed for the 7th time, the countdown will start at the set time state. Press S2 again to enter the adjustment function again. and stop the countdown.                                                    ⑤Stopwatch function: short press S1 four times, the display state is 00:00:00, and the colon is long on. Press S2 to start the stopwatch timing, press S2 again to stop the timing, and press S3 to clear the stopwatch when the timing is stopped.                                                    ⑥Counter function: short press S1 five times, the display state is 00:00:00, press S2, the counter will increase by 1, and press S3, the counter will be cleared.