Description: 【Automatic Brake Light】: This bicycle brake light turns on automatically when you brake, providing timely warning and enhancing cycling safe. No manual operation is needed 【Fit for Various Brake Types】: It is suitable for common bicycle brake systems such as V brakes, C clamps, and wire controlled disc brakes. Easy to install and suitable for various types of bicycles (mountain bikes, road bikes, folding bikes) 【Waterproof Design】: The light features a waterproof design that can withstand rainy or humid environments, ensuring normal use under various weather conditions 【Smart Sensing System】: The light comes with smart sensing system that turns on automatically when braking, reducing unnecessary operations 【Lightweight & Easy Installation】: Compact size and easy installation make it easy to carry without affecting the aesthetics of the vehicle or the riding experience Specification: Material: PP Size Chart: 3.2 cmx1.5 cm/1.26 inchx0.59 inch Package Includes: 1 Bike Rear Light Note: Please allow slightly errors due to manual measurement and different monitors.