Widely used in various vehicle racing, such as car, karting, motorcycle and bike; Can record 25 laps at one time; SUM: slowest time, fastest time, total time and average time; CLR: end timing and close IR receiving by short push, clear last record and start IR receiving by long push; Transmitter is powered by 2 x AA batteries, can work for 5h continuously; Auto urn off during idle to save power; Batteries need to be replaced after 5 hours of use to avoid weak signals; Take the batteries out of the box during long idle; Forbidden to point the laser to eyes, keep the product away from children.