PowerTac Slim OFF SET TACTICAL Weapon Mount For PowerTac E5/Cadet, Olight M10/M18/T10/T20, Fenix, JETBeam and many more 20mm Diameter size Flashlight heavy duty 20mm light mount, fit any 19-21mm Diameter tube flashlight Designed to be compatible with all weaver/picatinny style rails Only 20mm wide mount, slim and light weight, perfect for one CR123A flashlight tube Large knurled knob for secure "no-tool" rail mounting, quick release Constructed of aluminum with a black annodized finish for long lasting performance