Crimson Trace CMR-201 Rail Master Universal Red POWERFUL RED LASER: Features a 5mW peak, 620-670nm, Class 3R visible red laser - the brightest beam allowed by law. INSTANT ACTIVATION: Ambidextrous Tap-On / Tap-Off Controls for immediate laser activation from either side of the unit. OVER FOUR HOURS OF BATTERY LIFE: Powered by one 1/3N Battery (included). This product is eligible for Crimson Traces Free Batteries For Life Program. FITS: most pistols, rifles, and shotguns with M1913 Picatinny or similar Accessory Rail & 1-1/16" between the recoil lug and the trigger guard. EASY INSTALLATION: User installed- no gunsmithing required. Four fit inserts are included for specific firearm fit. Factory sighted at 50 feet, but is fully user adjustable for Windage and Elevation with provided tool. WARRANTY: 3 Year Manufacturer Warranty and FREE Batteries for Life Fits M1913/Picatinny Rails and Weaver Rail Adjustable Rail Laser Instant Activation - Tap On, Tap Off with auto shut off Battery Life & Type: Four Hour constant activation / 1/3 N 3V Lithium Battery Adjustable Windage and Elevation