The CMR-201 Rail MasterA(R) is a powerful and versatile laser sight designed to fit rail-equipped pistols, rifles and shotguns. The Rail Master locks onto Picatinny M1919 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. Mfg: Crimson Trace Corporation