Welcome to our Smart Rear Light product description Here are the key points you need to know: 1. Brake Sensing Function: The rear light features a brake sensing function that switches to brake light mode when deceleration is detected, emitting a strong light to improve cycling safety. 2. Intelligent Induction: The taillight automatically turns on in dark environments in slow flash or breathing light mode, and turns off after 30 seconds of no vibration, conserving battery power. 3. USB Charging: This rear light is USB rechargeable and features 4 blue LED power indicators for clear battery status visibility. 4. Waterproof Design: With an IP65 waterproof rating, the rear lights can be used normally on rainy days, adding to its versatility and reliability. 5. Versatile Installation: The rear light offers two installation methods - under the seat or on the vertical pipe - providing flexibility for installation in any suitable location. Product Size: 4*3.4*3.4cm Shipping Quantity: 1 piece Thank you for considering our Smart Rear Light. Safe cycling awaits with this advanced and reliable taillight