Knight's Free-Float RAS replaces the standard hand guards on the AR15. This is the handguard that is used on the Mk12 SPR/A, SPR/B, and Naval Special Warfare Command (NSWC) SPR aka Mk12 Mod1 or special purpose rifle.
This is also the rail used on the USMC SAM-R, and also the NSWC RECCE Rifle. KAC Rail are marked either "pn 99167" or "pn 21318"
Picatinny rails on all four sides allow endless possible mounting solutions for accessories such as sling mounts, a bipod, vertical forearm grips, flashlights and more. The RAS comes with three (3) 11 rib panels to help protect the rails from damage.
This is a new part from Knights Armament. Quad rail Picatinny 7075 anodized aluminum, complete with hardware to attach to receiver.