The Streamlight ProTac series expands into weapon-mounted lights with this 350 lumen light featuring a dedicated fixed-mount for Picatinny rails. It uses either a remote switch with momentary/constant on operation or a standard push-button tail switch, and can run on either a lithium battery or an easy-to-find alkaline battery.
Dual fuel - uses one AA alkaline or CR123A lithium battery (both included); also accepts AA lithium