2 rail. I've shot 18s with rifle gas like how sleek and precise These are. I'm able to put more money into functionality components then clone correct pieces similar to a ops brake and collar that I haven't got a can for. Two fireplace Management teams exist for the M4 https://marcoizpcm.blogocial.com/the-smart-trick-of-knights-armament-m4-rail-that-nobody-is-discussing-65495871