2 rail. I have shot 18s with rifle gasoline like how easy and accurate They can be. I can put extra money into general performance parts then clone proper pieces like a ops brake and collar that I haven't got a can for. AR15.COM is the globe's greatest firearm Local https://jaredhbrht.ampedpages.com/the-best-side-of-knights-armament-m4-quad-rail-56804216