Crimson Trace CMR-202 CTAN Universal Rail Mount Light Rail Master, Black Battery Life and Type: Four Hour constant activation / 1/3 N 3V Lithium Battery Class IIIA laser; 5mW or less Fits most M1913/Picatinny and Weaver style accessory rails on pistols, rifles and shotguns. Once you lock it on, it will not move thanks to advanced Secure-Lock Technology 100 Lumen LED White Light, with 2 Hour Instant Activation-Tap On, Tap Off with auto shut off