【Auto Brake Sensing】-This bike brake light can double-click to switch between manual mode/auto mode. Both modes have brake sensing technology, and auto light-up at maximum brightness to remind others. 【Manual & Auto Modes】- The smart bike tail light will automatically turn off after 30 seconds when it detects no movement, and once it is touched or the bike is detected moving, the light will automatically turn on again. Manual mode requires the taillight to be turned off by yourself. 【6 Light Modes & Waterproof】- Bicycle brake light has six flashing modes: constant on(60lm), breathing flashing(50lm), slow flashing(50lm), fast flashing(50lm), rhythmic flashing(50lm), and Eco flashing(30lm). IPX5 waterproof makes bicycle taillights suitable for any harsh weather. 【Light Sensor and Motion Sensor】- In auto mode, the taillight will be automatically turned off in natural light during the day, and will automatically turn on at night, but still have the brake function. When no motion is detected after 30 seconds, it will automatically sleep. Once touching it or detecting bike movement, the light will come on automatically (designed for energy saving and convenience). 【Durable Battery & Charge Indicator】- The bike light has a built-in 420mAh Li-ion battery, which can last for 9 hours (maximum brightness) running time when fully charged. Click the switch in the off state, and the indicator light will indicate the remaining power, No longer worry about forgetting to charge. 【Easy to install and remove】- Saddle mounting brackets and adjustable silicone straps are provided for mounting on the saddle rail or seat tube. If you need any help, please feel free to ask us your questions. The bike light is made of high-quality abs material, which is durable and has a long service life. Rechargeable: The rechargeable battery can be easily charged by usb charging cable, and it is easy to carry. Waterproof: The bike light is waterproof and can be used in rainy days, but it will not affect the use of your bicycle.