2 7/8" overall. Black ABS casing with one hand on/off rotating bezel. White LED. 74 lumens. Runtime: up to 11h. Beam distance: up to 92m. Peak Beam Intensity: up to 2124cd. Waterproof: up to 1m (IPX7). Comes with a black and gray adjustable nylon head strap, as well as a heavy duty rubber strap that will not slip off your climbing helmet. Uses three AAA batteries (included). Hang packaged.