What sets the M4 RAS besides other 2-piece quad rails in the marketplace is the fact it securely locks on the rifle’s barrel nut by way of a clamp and screw arrangement, which makes it an incredibly strong foundation on which to mount tactical components. Posted by BRAD on 23rd https://rasrail29528.tkzblog.com/29410318/what-does-knights-armament-m4-quad-rail-mean