What sets the M4 RAS other than other 2-piece quad rails available is usually that it securely locks to your rifle’s barrel nut by way of a clamp and screw arrangement, rendering it a very stable foundation on which to mount tactical extras. Involves 3 KAC 11 Rib Rail Panels. https://kacrasrail18384.blogzag.com/71211120/the-definitive-guide-to-kac-m4-ras