The Streamlight 88066 ProTac Rail Mount HL-X is a 1,000-lumen weapon-mounted light featuring a rail clamp designed to rapidly and securely attach/detach from rifles, carbines, and submachine guns with a MIL Standard 1913 Rail. It uses either a remote switch with momentary/constant on operation or a standard push-button tail switch, and can run on either two CR123A lithium batteries or one Streamlight rechargeable 18650 battery..