Multi functional: Can be used as a bicycle LED tail light, warning light or headlights. Except the bike handle bar, you can place it in the seat post, helmet bags and more. (Length of the strap: 7.677 inches/ 19.5 cm, can hold most bikes seat post) Super Cool for Cycling trip: If you are a person who like cycling trip, hiking and other outdoor activities, this durable light will be the essential in your journey. 5 Lighting Modes: Red highlight; Red Weaken; Red fast flashing; Red slow flashing; SOS flashing. (Highlight mode can be used for 5 hours) USB Rechargeable: Built-in rechargeable battery, it stops wasting your money to buy batteries for it. Ultra Bright and Waterproof Easy to install: Suitable for many sizes of handlebars or seat post Specifications LED: COB LED Shell Material: Waterproof ABS Brightness: 10 lumens Battery: rechargeable polymer ion battery Charging time: about 1.5 hours Use time: strong light gear for 5 hours; warning light for 32 hours How to use: On: click 1 time (0.5 second) Off: 5 lighting modes style need press 3 seconds. 4 lighting modes style just need press 1 second. Packing List Bicycle Taillight x 1 USB Charging Cable x 1 Mounting Strap x 1 *Please do not immerse the USB port in water though it is waterproof.