Features: 1. Shutdown function: power can be turned off and the clock does not need to be reset (most stopwatches on the market currently do not have a shutdown function).2. Key mute function: It can be muted and used under quiet situations. 3. Time and calendar function: display year, month, day, hour, minute, second, week, 12 or 24 hour system optional. 4. Stopwatch function: 3 rows display, segmented memory storage, precise value up to 1 or 100 seconds, the longest time is 9 hours 59 minutes 59 seconds, 5. The fastest, slowest, and average value can be viewed. When searching memory data, you can check up and down. Each function is easy to use. 6. Countdown function: It can set the countdown function and times counting function. The longest countdown time is 9 hours, 59 minutes and 59 seconds. 7. Daily alarm clock function: can quickly turn on or off the alarm clock. 8. Metronome function: beat frequency can be selected 5 times or minute- 320 times or minute (multiple of 5 times) and has times counting function Specifications: Model: YS810 or YS830 or YS860 or YS8100 Color: white or black Display: 3 rows display of 10 or 30 or 60 or 100 tracks Material: ABS plastic shell Battery: built-in CR2032 button battery Display size: 35 x 23.5mm or 1.38 x 0.93" Product size: 75 x 62 x 21mm or 2.95 x 2.44 x 0.83" Gross weight: 70g