Guntec USA has been manufacturing AR-15, AR-308 and AR 9mm accessories since 1989. Their goal is to distribute excellent quality, at an economical value. FeaturesThreads begin approx 1.25a ^2 down the shroudDual Purpose Unit, Functions As A Barrel Shroud And A Muzzle Compensator!Slips Over Barrel And Threads Down From The InsideMulti Porting "Gatling Gun" Style Muzzle Comp Reduces Felt Recoil Up To 70 PercentCovers 1 3/8a ^2 of the Barrel