The Surefire HUB Suppressor Muzzle Adapter is designed for .223 Rem/5.56 NATO calibers and features a 1 3/8"x24 thread pattern. This 2-inch adapter allows for the quick attachment of HUB suppressors to SureFire SOCOM Fast-Attach muzzle devices.Key FeaturesFast-Attach Compatibility: Converts 1 3/8-24 thread-pattern HUB suppressors and accessories for use with SOCOM muzzle devices.Precision-Machined: Crafted with the same dimensions and tolerances as Surefire's combat-proven suppressor back section for a secure fit.Durable Construction: Manufactured from stainless steel and black nitride-coated for enhanced durability and longevity.