The MB556K muzzle brake fits the Colt Commando, M4, M16, HK 416, and other 5.56mm (.223 cal.) semi-auto, bolt-action, or assault rifles with Mil-Spec 1/2-28 muzzle threads. The MB556K muzzle brake greatly reduces both recoil and up-and-right muzzle movement to keep you on target for faster follow-up shots, while their patented Impulse Diffusion design minimizes side blast and rear-directed concussion effects. (To see one in action, click on the video button at left.) Machined from heat-treated stainless steel, finished in tough corrosion-resistant SureCoat, all SureFire muzzle brakes are extremely resistant to gas and particle erosion and will perform perfectly for thousands of rounds.