This is a tool used to measure the amount of time something takes. For example, to learn how soon a car can reach 60 miles per hour, or how much time it takes a runner to run 40 yards.
Press a button to start the time and press it again to stop the time. The time is displayed on the screen of it. The time continues running in background!!
Use the volume buttons: UP to Star/Stop time. Use the DOWN button to Lap/Reset time.