Brehn | Ultra-Smart Bike Tail LightSmart rear light Thanks to a sensitive acceleration sensor and a powerful microcontroller unit, the three stage digital filter algorithm precisely detects braking and automatically switches to brake light mode. USB rechargeable The fully charged 600 mAh battery takes 3 hours to charge, and with the included USB cable, the light can be used for 8 to 12 hours, eliminating the need for frequent recharging. Waterproof according to IP6 IPX 6 protection