Serfas' True 500 Light is what you need to see the road or trail at night. Lightweight, compact, and super bright - the TSL-500 will deliver when you need it most. It comes with a rechargeable Li-Ion Battery, USB Charger cable, USB Wall Adapter, Handlebar and Helmet Mounting systems, and a limited lifetime warranty. Serfas is setting the benchmark in high-powered LED lighting technology by testing it lights in house using a 20 N.I.S.T. Traceable Standard Intergrating Sphere. Hence the name True lights, when you buy a Serfas light - you are guaranteed to get what you paid for. Additional Li-Ion batteries available for purchase, charge up 2 batteries and ride all night!