[Automatic]-The Smart Bike Tail Light features a smart break sensor and built-in accelerometer that detects breaking and signals to cars and other bikers that you are slowing down. This feature can be used in Flashing or Pulsing Mode, and switches the tail light to Steady On light within 3 seconds of detecting deceleration. [Muti-Mode]-Our bike tail light lets you choose between four different light modes: Flashing Mode, Breathing (Gradual Pulse) Mode, Strobe Mode, and Steady On Mode. Each mode uses smart technology to detect daytime and nighttime conditions to adjust the brightness levels, and each light mode transitions into the power-save mode after 30 seconds of daytime inactivity. The Strobe and Steady On Mode also include this power-save feature for nighttime inactivity. [Waterproof]-Smart Tail Light is USB rechargeable and can easily be removed from the bike mount for hassle-free recharging. It is IP65 Waterproof to withstand all types of weather conditions. (Please be sure to secure the rubber USB port plug to prevent water from entering the port). [Easy to Use]-To install the Smart Tail Light, simply mount the device to the bike's saddle bracket or seat rail and secure it with the heavy-duty cable ties or bands. No additional tools are required! In addition to keeping bicyclists safe, our smart light can be attached to infant strollers, wheelchairs, pet harnesses, children's bikes, backpacks, and helmets. [Ideal Gift]-This Tail Light is perfect as a birthday gift, Christmas gift or holiday gift for a friend, family member or classmate who needs it and will love it.