Smart Auto Brake Sensing Warning This bicycle rear light auto-brightens when braking, instantly alerting rear vehicles to your deceleration and reducing collision risks for night cycling. Vibration Auto Start Stop Mode The taillight wakes up on bike vibration and auto-sleeps after inactivity, saving battery power and eliminating tedious manual on/off operations for daily use. Dual Mount Bracket Universal Fit Equipped with dual mount brackets, it fits bike seat posts and seat rails stably, meeting different bike installation needs without extra accessories. Type-C Charging IPX4 Waterproof Type-C fast charging port enables 1hr full charge with IPX4 waterproof rating, resisting rain and splashes for all-weather cycling commutes. Multi-Mode LED Bright Light 4 lighting modes (solid/flash/slow flash/breath) with bright red LED light, ensuring high visibility in low light for night and urban riding. Bicycle Rear Light;Smart Brake Sensing Light;Auto Start Stop Taillight;Dual Mount Bracket Light;Type-C Charging Bike Light;IPX4 Waterproof Taillight;LED Bicycle Rear Light;Night Cycling Light;Cycling Taillight;Bike Brake Light;Vibration Activated Light;Commute Bike Light;Seat Post Bike Light;High Visibility Taillight;Red LED Bike Light;Bicycle Accessories;MTB Rear Light;Road Bike Taillight;All Weather Cycling Light;Smart Cycling Light