Product Description Easy to install. Mounts to any bike quickly and easily. Safety guaranteed. The red light can be used for safety and warning. Rechargeable. A 180mA lithium-battery and a USB cable is included. No battery replacement. 2 light modes: Constant on/flashing Long runtime. Lasting up to 3.5 hours (constant on) or 6 hours (flashing) on a single charge. Water resistant. IPX4. Protected against splashing water from all angles. Stable. Remain securely locked in position, even during off-road use. Widely used. This tail light provides brilliant illumination for all bikes - racing, trekking, city, children's bikes and mountain bikes, and can be mounted on handlebar, seat riser, backpack, helmet and more. Charging voltage: 5VDC Charging current: 1-2A Note: This light is suitable for ropes with 20-37cm/ 7.87- 14.57in diameters.