The TWM-852XL Xtreme Lumens? Tactical Weapon-Mounted Long Gun Light uses an LED rated 850 lumens for 1.75 hours providing a beam distance of 245 meters. The rear-facing single switch provides both momentary and constant-on lighting operation. Designed to securely attach to a long gun Picatinny rail, the IP-X7 rated waterproof housing is constructed from aircraft-grade 6061-T6 aluminum. The TWM-852XL comes preinstalled with one set (2) cross-rail inserts. An Allen wrench and 2 CR123 lithium-metal batteries and also included for quick installation and operation. (Not compatible with rechargeable batteries.) Specifications: Xtreme Lumens: Yes Flashlight Lumens: 850 Beam Distance: 245 m Candela: 15,000 Drop Rating: 2 m Dust/Water Rating: IP-X7 Waterproof Flashlight Runtime: 1.75 Switch Function: Momentary or constant-on Length: 3.5 in (89 mm) Width: 1.5 in (38 mm) Depth: 1.5 in (38 mm) Weight: 4.5 oz (128g) Head Diameter: 1.2 in (30 mm) Light Source: LED Case Material: Aircraft-grade 6061-T6 Aluminum w/Type III Hard Anodized Finish Body Color: Black Quantity of Batteries: 2 Power Source: CR123 Lithium Primary Batteries Package Contents: Light w/set (2) pre-installed cross-rail inserts, Allen wrench, 2 CR123 batteries US Patent: 9,713,217 Warranty: Limited Lifetime