This tactical light from Streamlight gives you more bang for your buck than any mounted light out there. It is shockproof, waterproof, and virtually indestructable! The rails mount directly to most handguns with rails as well as long guns with 1913 (Picatinny-style) rails. Up to 2.5 hours of continuous run time. Operating temperature of -40F to 120F. Fits all light bearing holsters. It comes with a "no excuse" lifetime warranty, making this light a sure winner. With batteries, the light weighs a mere 4.18 ounces. Adapters are available for the following guns: Mossberg Shotguns (12 gauge), 12 ga. Shotguns, with extended magazine tubesRemington 870, AR-15/M-16, MP-5, HK USP (Full Size) Handgun, S&W TSW,99