CAR Single-Insulated Round Carbine Handguard

also known as the skinny handguard.

Factory original, round handguards as you would find on a GAU5 -- these are the best:  Black polymer with single aluminum insulation.

Fits M4 and AR15 rifles with a front sight base and M4 handguard plate.  These differ from the Colt M4 handguards which are oval and double insulated

Made by DoubleStar.  DoubleStar and Ace have been USGI contractors for years.