A built-in integrated accelerometer ensures accurate brake detection, the rear light automatically turn to brake modes to warn the car from behind when decelerating or emergency , great for riding on nights. The flashing light turn on automatically in low brightness and turn off in high-intensity light in Fast Flash and Breathing mode. Saddle fit aluminum alloy system and tube fit straps, whatever you want to put on-saddle or tubes, bicycle or helmet, easily to install in seconds without any tools. The taillight can be easily by charging cable via computers, chargers or power bank. Rear light cover with anybody aluminum alloy case, not worry about the light get wet by rain. Has excellent vibration resistance, can be used for any terrain (Tips: Please turn the light mode to the steady on if you wanna use it in the daytime. because This taillight has a smart light sensing function. Light intensity be automatically dimmed under strong light to reduce the power consumption). Colour:Black Material:PC+ABS Package Contents: 1 * Smart Bike Tail Light Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.