MULTIFUNCTIONAL SAFETY LIGHT: Easy to install. Lightweight and durable bike tail light that can be mounted on all bikes, children's bike, adult bicycle, handlebars, seat posts, dog collars or anywhere. It also can be used as helmet lights, backpack lights, warning lights and moreSET YOUR OWN LIGHT MODES: 5 light mode options: Strobe(9 hours), Slow Strobe(56 hours), Meteor Flash(14 hours), Tai Chi Flash(17 hours), Breathing Flash(8 hours). You can switch different modes according to your needs and different occasions to get the best lighting experienceNO BATTERIES REQUIRED: Built in USB charge port for this bike rear light (USB cable included). Please charge it when the indicator light is red. It will turn green when fully chargedWATERPROOF BICYCLE TAIL LIGHT: The taillight is made of IPX5 rated water resistant material to ensure a safe use in heavy rain