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 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)