Sl Waterproof Smart Rear Sensor Led Bike Light Auto Brake Sensor (1 PieceblackDescription GUOXING Start the brakes, instantly highlight, automatically calibrate and identify the up and downhill road section optimization program algorithm, the big pit vibration mitigation belt will still activate the brake warning Brake induction, direct USB charging, smart light detection, LED lamp beads. The taillights are equipped with a 350mAh high-capacity battery for longer battery life. Portable USB charging,make your travel more convenient. Mobile power, mobile phone charger charging, can be charged anytime, anywhere. When the back cover glows green, it indicates that the back light is full. Not afraid of muddy washing, not afraid of any bad weather. Threaded and disassembled for easy loading at any time. Compact and lightweight, easy to carry. Notice: Actual color may be slightly different from the image due to different monitor and light effect Please allow 1-3cm deviation due to manual measurement Delivery Quantity: 1 Piece Product color: black Product size: as shown