1. Luminous display, with luminous button, press once to light up for 4 seconds, which is convenient for use at night. 2. Ultra-long timing range, stopwatch and countdown can count up to 29 hours, 59 minutes and 59 seconds, and can be cyclically timed. 3. The countdown can be set to cycle or not to cycle, the is 29 hours, 59 minutes and 59 seconds, and the reminder time can be set freely, which is convenient for fitness or daily use. 4. It can be turned off to save energy. Long standby time, it can be used for about two years after changing the battery. 5. Life waterproof, anti-rain, sweat, splash water. Functions: 1. Stopwatch: 0.01 second accuracy, the time is 29 hours 59 minutes 59 seconds. 2. Alarm clock: daily alarm clock can be set, the alarm clock can be turned on or off. 3. Countdown: The is 29 hours, 59 minutes and 59 seconds, and the reminder time can be set. 4. Cycle time: the time is 29 hours 59 minutes and 59 seconds, and the reminder time can be set. 5. Luminous display: with luminous button, press once to light up for 4 seconds. 6. Clock calendar: 24-hour clock, year, month, day and week display. 7. Hourly hour: can be turned on or off. 8. Can be shut down: can be shut down when not in use, and then back on after shutting down, the memory is still. 9. Mute: can turn on or off the sound of the keys. Function: clock calendar / alarm clock / stopwatch / countdown / sound switch / shutdown function / luminous / 29 hours long timekeeping Accuracy: 0.01 second Battery: CR2032 button battery (included) Tips: The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use Colour:Green Material:ABS Package Contents: 1 x 30h Chronometer 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. 30h Stopwatch Timerr 30h Chronometer Handheld Pocket Stopwatch LCD Stop Watch Digital Sport Stopwatch