[Brake Sensing] - This bike brake light can double-click to switch between manual and automatic modes. Both modes feature brake sensing technology and operate at maximum brightness to alert others. [Manual & Automatic Modes] - The smart bike tail light automatically turns off when no movement is detected, and turns back on when motion is sensed or the light is touched. In manual mode, the user must turn the light off manually. [Durable Battery & Charge Indicator] - The bike light has a built-in 420mAh battery, providing up to 9 hours of runtime at maximum brightness when fully charged. Press the switch when the light is off to check the battery level via the indicator light. No need to worry about forgetting to charge. [6 Light Modes & Waterproof] - This bicycle brake light offers six lighting modes: constant on (60lm), breathing flash (50lm), slow flash (50lm), fast flash (50lm), rhythmic flash (50lm), and steady flash (30lm). IPX5 waterproof rating ensures reliable performance in all weather conditions. [2 Mounting Options] - The bike taillight comes with two mounting options: attach it under the saddle using the included bracket or secure it to the seatpost with the adjustable silicone strap. The design allows for quick and easy installation, removal, and reattachment, making it convenient to take off for charging. Color: Black Material: Aluminum alloy + plastic Package Contents: 1 x bicycle taillight 1 x USB cable 1 x base bracket 2 x anti-slip rubber pads 1 x English manual Note: Only the items listed above are included. Light reflection and display differences may cause slight color variations between the image and the actual product. Measurement error is +/- 1-3cm.