Knights Armament (KAC)
KAC’s iconic Ribbed Rail Panels have seen use all over the globe on US military M4 Carbines. The lightweight polymer panels are ribbed for an enhanced grip, and help insulate the support hand from barrel heat. While originally designed for use on the KAC M4 RIS and M4 RAS rails, these panels are also compatible with many other railed handguards.
These are "new old stock" rail covers made after Knights moved from Vero Beach, but before 2009 or so, when the rails started to have CAGE Code numbers also attached. Some collectors would consider these slightly more desirable than CAGE Code marked, which are current production.
Funny fact: The hardest to find rail covers are the 2-rib and 5-rib