MULTIFUNCTIONAL SAFETY LIGHT: Easy to install. Lightweight and durable taillight to mount on any bike, kids, adults, handlebars, seatposts, dog collars or anywhere else. It can also be used as a helmet light, backpack light, warning light, etc. 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 modes according to your needs and different occasions to get the best lighting experience NO BATTERY REQUIRED: Built-in USB charging port for this bike tail light (USB cable included). Please charge it when the light is red. It will turn green when fully charged WATERPROOF BIKE TAIL LIGHT: The rear light is made of IPX5 rated water resistant material to ensure safe use in rainy weather