Thank you for coming to our shop, I hope it is to your satisfaction Item Name: Bike Taillight Battery: 600mAh Features: Rechargeable, Waterproof, Easy Installation Size Details: Length: 12.9c more→m/5.08" (Approx.) Specifications: It is constructed of ABS material, which is waterproof, wear-resistant and durable. Comes with USB port, not only can be used as a lighting, but also as a portable rechargeable battery can be given to computer, car charger, USB socket and power bank during night cycling. Designed to be lightweight, so it fits easily in your pocket or car bag Tail light emits an eye-catching wide-angle beam that can be seen from blocks away, so you don't have to worry