Facet mounted process by having an built-in MILSTD 1913 rail piece for sighting techniques. Created for use with the M203. Posted by BRAD on twenty third Jan 2020 Great products, fits like a glove, strong, sound and can have a beating. Took me a minute to install it due to https://jasperunhyn.mdkblog.com/35216436/rumored-buzz-on-kac-drop-in-rail