Crimson Trace Corporation, RailMaster Laser, Universal Rail Mount, Tan Switch activation Red laser Factory sighted at 50Ft .5 inch diameter at 50 feet The CMR-201 Rail Master(R) is a powerful and versatile laser sight designed to fit rail-equipped pistols, rifles and shotguns. The Rail Master locks onto Picatinny M1913 or Weaver-style accessory rails with Crimson Trace's Secure-Lock Technology(TM). Once locked on, it will not move under recoil or handling. The universal design of the Rail Master offers quick Instant Activation(TM) by simply tapping on and tapping off from either side with the ambidextrous activation control tabs. Additionally, the CMR-201 features a 5 minute auto-shut off feature that will power down the unit to conserve battery life if the laser sight is unintentionally activated. Versatile and flexible, the CMR-201 laser sight includes four (4) different inserts to adapt to various firearm platforms. The unit features a powerful 5mW red laser that will run for over four (4) hours on a single 1/3N Lithium battery. Rail Master is factory sighted at 50', but is fully user adjustable for windage and elevation. Fits pistols*, rifles, and shotguns with M1913 Picatinny or Weaver-style Accessory Rail