JMac Customs 2C 1/2-28 2-Port Muzzle Brake with Keymount Black. The RRD-2C was created by removing the 2 smallest ports from the RRD-4C creating a more compact package while still maintaining the ability to mitigate recoil. JMac Customs recommends that all suppressor mounts be installed and checked for alignment by a certified professional. Serious damage could result to your suppressor/firearm and physical harm is possible if installed/used incorrectly. All suppressor mounts MUST be tight against the shoulder or face of the barrel using shims or face-milling method. Contact us if you have any questions or need a recommendation for professional installation. JMac Customs LLC is not liable for injury damage or death related to the usage of this product. This is a licensed product through Dead Air Silencers. Specifications for JMac Customs 2C 1/2-28 Muzzle Brake w/ Keymount: Manufacturer: JMac Customs Color: Black Finish: Nitride Fabric/Material: 17-4PH Stainless Steel Threads per Inch: 1/2x28 Gun Make: Kalashnikov USA AR Platform Israel Weapon Industries (IWI) Grand Power Century Arms CZ Heckler & Koch Ruger Length: 2.23 in Condition: New Features of JMac Customs 2C 1/2-28 Muzzle Brake w/ Keymount 2 Port Muzzle Brake with Keymount KeyMo & KeyMicro Suppressor compatible 10mm Bore Added length: 1.53" Not intended or recommend for barrels shorter than 10.5 Can be permanently attached to a 14.5" barrel to achieve 16" OAL. Package Contents: JMac Customs 2C 1/2-28 Muzzle Brake w/ Keymount JMac Customs RRD-2C-28S-KM: 2C 1/2-28 2-Port Muzzle Brake with Keymount Black