Facet mounted procedure with the integrated MILSTD 1913 rail piece for sighting units. Created for use With all the M203. Posted by BRAD on 23rd Jan 2020 Magnificent products, matches just like a glove, durable, stable and will have a beating. Took me a minute to set up it simply https://emilioznxhq.onzeblog.com/29530957/ras-rail-things-to-know-before-you-buy