Miniature Short Holographic Sight Adjustable | Slide ON & Tighten ONFits all AR15/M16A1 model railingAvailable in Black or CoyoteSee through insert100% die cast metal1 1/4" in length (3.2cm). This is 3/4" shorter than the other holographic sightAdjust to tighten on and off railing easilyNo a functional optic. Some fans use a green or red permanent marker to draw a small dot on the lens