The SureFire G2 flashlight is powered by two lithium batteries (10-year shelf life) and made of Nitrolon, a proprietary polymer compound that is lightweight, corrosion-proof and non-conductive. A molded-in gridlock pattern allows for a sure grip in any weather, and? although three to four times brighter than a typical 2-D cell flashlight? this lightweight powerhouse is less than five inches long; making it ideal when space is at a premium and weight is an issue. The G2 features unique switching originally developed for law enforcement? twist for constant on, or depress the tailcap button for momentary illumination or emergency signaling. Features: Batteries - Two SureFire lithium 123A 3.0 Volt with 10-year shelf life Lamp assembly/Runtime - SureFire P60 xenon gas-filled lamp assembly with 65 lumens output for one hour, also accepts optional P61 ult