This is the SureFire 300a Scout powered by one 123A lithium battery. This lightweight scout light has the capability of 110 lumens. The Scout mounts to any Mil-spec Picatinny rail with the included thumbscrew mount. WeaponLight activation is achieved by clicking the tailcap pushbutton switch or, for fingertip control without altering your grip on the weapon, by depressing the included pressure-activated tape switch. The ultra-compact, durable Mini Scout Light was built to withstand the rigors of combat without weighing your weapon down.