2 rail. I've shot 18s with rifle fuel like how clean and exact They can be. I can put more money into efficiency elements then clone right sections just like a ops brake and collar that I don't have a can for. Posted by BRAD on 23rd Jan 2020 Magnificent https://kac-m4-rail38368.mpeblog.com/53064798/what-does-knights-armament-m4-quad-rail-mean