Streamlight Pro Tac Rail Mount 2 Dedicated Fixed-Mount Long Gun Light is part of the 6000 series machined aircraft aluminum with anodized finish. The Gun Light produces 625 lumens of light. It is shock mounted, AR coated, with an impact resistant BOROFLOAT glass lens. The light source is C4 LED technology, impervious to shock with a 50,000 hour lifetime. TIR optic produces a concentrated beam with optimum peripheral illumination. The multi function, push button tactical tail switch or dual remote pressure switch with latching push button turn it on and off. One handed operation of momentary, variable intensity or strobe mode. TEN-TAP programmable switch allows user selection of one of three different programs: high/strobe, high only, or low/high. Runs on two CR123A lithium batteries which are included. Length is 5.00 inches, 1.20 inches wide, and height is 1.50 inches.