A cheap and essential safety feature for your bike. The brightness of this LED light is impressive, helping you feel safe on your bike, and the shell is waterproof. Secure the light onto your bike seat post by fastening the velcro on the adjustable strap. Turn the light on with the press of a button. There are 4 different light modes, including strong light and flashing light. The light is USB charged, requiring 2-hours of charging time to provide 3-6 hours of working time, depending on what light mode you are using.