4 Modes Bike Backlight: Comes with 1 switch to complete 4 modes, including Full Brightness / Chase Mode / Quick Chase Mode / Flashlight Mode. can be seen from a long distance, it is also easy to be noticed by others in the dark, increasing visibility and safetyUSB Charging Design:Built-in 220 mAh rechargeable lithium battery and USB port design, you can use any device with USB port to charge the bike taillight; there is a USB cable on each bike taillight, allowing you to charge from your computer, mobile power or any device with USB port.Automatic power-off system when fully charged.Wide Application: These lights not only provide lighting for most bikes, such as racing bikes, mountain bikes, etc., but they are also suitable for attaching to most bike frames, posts, handlebars or helmets, hooking on your belt, running gear, reflective undershirts, backpacks, dog collars, etc.; they can also be carried around, mounted on clothing, helmets, or anywhere else you wantPackage Content: You will receive 2 USB rechargeable led bike tail light and include 2 USB connection cable, the number is enough for your daily use and replacementEasy to Install: The silicone mounting for the bike rear light comes with 4 openings for you to mount on handlebars and posts, and the bike tail light fits around most sizes of handlebars and seat posts, you don't need other tools to install it