1. Battery Powered: This wire less timer has a built in 1500mAh lithium ion battery that can be charged for 5 hours and run for 8 hours. Featuring a battery percentage reminder design and side switch buttons, easy to operate. 2. Technical Parameters: The effective lighting distance of the wire less sprint timer is greater than 8 meters, meeting more scene requirements. Using a 5 digits display, accurate to 0.001 seconds, ensuring accurate and timing. 3. Automatic Reset: When triggered another time, the wire less sprint timer will automatically reset and enter the another round of timing, without the need for manual reset. The timing error for one hour is less than 0.001 seconds. 4. Versatile Use: This wire less timer is suitable for timing starting and ending at the same position, is a great training device for motorcycle timing, pile driving timing, balance bike, roller skating, pet training, and field training competitions. 5. Portable and Practical: The run race timer is made of excellent materials, with high strength and wear . Equipped with a portable tool box, waterproof and shockproof, convenient for storage and carrying. Specification: Item Type: wire less Sprint Timer Material: Aluminum, PC, ABS Power Supply: 1 x Lithium Ion Battery 1500mAh (Built in) Charging Input Voltage: DC 5V Package List: 1 x Timer1 x Reflector2 x Floor Stand1 x Charging Cable1 x Storage Box1 x User Manual Note: 1. It is strictly forbidden to stare at the emission hole in the work with the eyes. 2. The product does not come with a power adapter, any power adapter that outputs DC 5V can the product.