Brake sensing auto light vibration detectionduring riding, the tail light detects braking through g-sensor changes such as braking or vibration. When braking is sensed, the light automatically switches to maximum brightness for about 3 seconds in any mode to warn vehicles and pedestrians behind. Built-in light and vibration sensors enable automatic on off: the light turns on in low-light conditions, switches off after about 30 seconds of being stationary, and reactivates instantly when vibration is detected. *Please refer to images for supported modes. Multiple lighting modes with one-click controlthe rear light features a high-transparency pc lens and bright led for soft yet clear illumination with wide visibility. It supports free switching between lighting modes using a single button: slow flash breathing flash burst flash always on simple one-click operation allows quick mode changes while riding, with a memory function that recalls the last used mode. Ipx6 waterproof & lightweight shock-resistant design rated ipx6 waterproof to handle sudden rain not recommended for long-term rain exposure or submersion . Impact-resistant housing weighs only 22g. Compact size approx. 3 × 2.9 × 3.8 Cm makes it easy to carry in a cycling bag or pocket.