MUZZLE BRAKE QD 5.56MM 1/2X28 SFMB-556-1/2-28 Manufacturer Model Number: SFMB-556-1/2-28 Manufacturer: SureFire Model: Muzzle Brake/Silencer Adapter Caliber: 223 Rem | 5.56 NATO Type: Accessory-Muzzle Brakes Item Type: Accessory Overall Length: 2.7" Shipping Weight: 0.35 Optic Adjustable Objective: false Optic Reticle Illuminated: false