Gobike Super Bright USB Rechargeable LED Bicycle Tail Light USB Charged -- Automatically cut off power supply upon fully charged Four modes -- Long light, Slow flash, Quick flash, Strobe Simply to install -- Without any tools, you can install this taillight in seconds IPX-4 waterproof -- Keep this bicycle taillight function in any situation Ultra bright -- Equip your bike with this taillight can attract the attention of other vehicles at a far distance