The NEBO EINSTEIN® Series is inspired by, obviously, Albert Einstein, who had a brilliant mind and a knack for innovation. He was fascinated by light and its many uses, and the EINSTEIN® Series lights are inspired by his passion. Features: Low-profile, compact design, this headlamp is the perfect companion for any outdoor enthusiast Five different light modes Never run out of light with the flex fuel feature, you can also power the light with two CR123A alkaline batteries USB-C rechargeable battery provides up to 18 hours of use Durable ABS and aluminum construction Water resistant (IPX4) One button controls power and modes 1 USB-C to USB charging cable Powered by included lithium ion rechargeable battery