The bicycle tail light with built-in built-in accelerometer ensures accurate brake detection. It will light up when braking and automatically switch to brake light mode when decelerating. When driving in low light, the taillights will automatically turn on and off in high light. It is not only used as a bicycle taillight, but also mainly used as a brake light. Put the bicycle brake light bracket on the seat cushion rail , the saddle-shaped aluminum alloy system and the tubular fastening strap. Whether you want to wear it on the saddle or the tube, the bike or the helmet, it can be easily installed in seconds, without any tools. Color: as shown picture Size: 7.6*5.4*8.5CM Quantity sold: 2pcs Name: Night Bike Headlights (Rear Lights). Charging Time: 2-3 hours Lamp beads: LED combination Battery life: 4-30 hours Lumens: up to 150 lumens Charging method: USB direct charging Mode: white light car headlights\/taillights red light car light strong-medium-flashing-fast flashing About chromatic aberration: The goods sold are all taken in kind, but due to different lighting, monitors, etc., there will be a little color difference, which is a normal phenomenon, not a quality problem About the size: The dimensions of the products sold are all measured manually. Due to different measurement methods and tools, there may be an error of 1-2mm, which is normal