SMART SPEED SENSING & EASY to INSTALL - Automatically switch to High light mode when decelerating, ultra-bright for 5 secs lights warning back rider to enhance your safety. You can Mount it with metal mounting bracket or the adjustable silicone strap. BATTERY SAVING - The bike smart brake light will be automatically switch off when detect in no motion after 30 secs. Once touch it or detect the bike moving, the light will automatically turn on. Its more convenience to use and save your valuable time. INLIGENT ON - 3 light modes for your choice: slow flash, breathing flicker and steady on. Under the weak light circumstance, this light sensing bike taillight brake sensor will automatically detect it and turn on for eye-catching back rider and car driver. USB RECHARGEABLE & SUPER LONG STANDBY - Support quickly charging, the rechargeable bike tail light can be power by 2A cable. Built-in 500mAh Li-ion batterty, the taillight lasting 50 hours runing time in full charging of 20-30 minutes. IP65 WATER RESISTANT & SHOCK RESISTANT - Adopted with aluminum alloy, the braking tail light has a nice touch and awesome appearance. It against splashing water from any angle, withstands all adverse weather conditions. If you have any product issuce , please contact us asap. We will try our best to help you to slove it.