Description: 【Long Term】: This bicycle taillight is equipped with RC2450, with a battery life of up to 96 h, up to 197 hours in constant light mode, up to 133 hours in flash mode, up to 192 hours in mode, and up to 138 hours in breathing flash mode 【Smart Brake Sensing Technology】: Using a high precision chip, smart brake sensing technology automatically detects braking action and responds immediately to improve safety 【Vibration and Automatic Sleep Mode】: The bicycle tail rear light will intelligently enter sleep mode after 40 seconds of inactivity to save life, and will reactivate immediately when vibration is detected to ensure it is always available 【IP55 Waterproof Rating】: With an advanced waterproof structure, this smart bike tail light can withstand adverse weather conditions and ensure reliable performance even in heavy rain or stormy weather 【Easy to Install】: The smart brake bike tail light can be quickly and safely installed or removed for daily use. Maintain stability during riding Specification: Material:PP Waterproof: IP55 Auto sleep: 40S Size Chart: 3.1cmx3.1cmx2.2cm/1.22inchx1.22inchx0.87inch Package Includes: 1 Bicycle Tail Light Note: Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.