Knight's M5 R.A.S. replaces the standard hand guards on 20 inch MILSPEC barrels. Installation takes about 5-10 minutes and only requires an allen wrench. Picatinny rails on all four sides allow endless possible mounting solutions for accessories such as sling mounts, vertical forearm grips, flashlights and more. The M5 R.A.S. comes with three 11 rib panels to help protect the rails from battle damage.