Triple color Red, Green, and Blue Dot Compact Tube Reflex Optic with 35mm objective lens allows the shooter a wide field of view to quickly acquire, aim, and engage their target. AR15/M4 11/2" height 30mm cantilever weaver type mount will fit on virtually any Weaver, Picatinny, MIL-STD 1913 type rails. Features : LED (Light Emitting Diode) 100% Safe for the Eyes Unlimited Eye Relief for flexible mounting Rheostat Knob with Three Brightness Levels for each of the Red, Green, and Blue Dot reticles