1.【LAP AND SPLIT MEASUREMENT FUNCTION】：YS-810 saves 10 reminders for events. It can measure up to 10 hours in 1/100 second. YS-8100Allow to record in both the lap and split time with the ability to store 100 memories for events. It also can measure up to 10 hours in 1/100 seconds. 2.【MEMORY RECALLED FUNCTION】：YS-810 Up to 10 measured values can be stored in the memory.YS-8100 Up to 100 measurements can be stored in memory, and they can be recalled with the fastest lap, slowest lap and average lap time, also can recall each split/lap time in the order. 3.【THREE ROWS DIGITAL DISPLAY LARGE SCREEN】： Lap time, split time and the total continue-moving time are displayed in the same screen with three separated rows.It is suitable for sports coach, easy to view time and record date. 4.【MULTIFUNCTION STOPWATCH】：Stopwatch with countdown timer, calendar clock and alarm allow you to manage the time better in sports and daily life. 5.【COUNTDOWN TIMER】：The stopwatch is with the countdown function, can be used as a countdown timer. Press the "MODE" button to enter into the countdown timer mode. The "TR" will be displayed on the screen. When the countdown time is over, it will make the alarm sound.