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 more SET 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 experience NO 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 charged WATERPROOF BICYCLE TAIL LIGHT: The taillight is made of IPX5 rated water resistant material to ensure a safe use in heavy rain WARRANTY: Any problem can contact with us, and we will try to solve it within 24 hours.