Knight's Armament Long FF RAS, MK12 Mod 1 w/3-ribbed panels
Knight's Free-Float RAS replaces the standard hand guards on the AR15. This is the handguard that is used on the 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.
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 11 rib panels to help protect the rails from damage.
Rail is marked, "pn 99167"