Aggressive, scallop-type cuts deliver superior gas dispersion to help stabilize the muzzle during periods of sustained fire. Special internal blast chamber with side-facing ports helps reduce recoil with no adverse effect on gas system function. Also provides enough flash suppression to keep flash out of the shooter's line of sight. Wrench flats directly over the internal threads ease installation. All models include a peel washer for precise indexing of the side ports. The CQB556 is designed primarily for entry teams and other operators working in confined spaces like buildings. Directs the entire force of the muzzle blast forward to protect the shooter and team members next to him Mfg: Primary Weapons SPECS: Steel, black, parkerized. Includes washer. CQB556 models fit AR-15/M16/M4 and clones chambered in .223/5.56mm, with A 1/2"-28 tpi RH muzzle threads. CQB556 - 2A 3/4" (7cm) long x 13/8" (3.5cm) diameter. 9.1 oz. (258g) wt. A 1/2"-28 tpi RH thread