Forward Controls Design Muzzle Brake 5/8x24 QPQ Black. 1210RF has external 0.900 x 24 threads compatible with sound suppressors with 0.900 x 24 threads (such as CGS and Plan B) and adapters such as Rearden's Atlas adapter. Do not use a crush washer if this is going to be a suppressor host Specifications for Forward Controls Design 1210RF Muzzle Brake: Manufacturer: Forward Controls Design Color: Black Finish: QPQ Fabric/Material: 17-4 Stainless Steel Threads per Inch: 5/8x24 Length: 1.725 in Weight: 2.17 oz Package Contents: Forward Controls Design 1210RF Muzzle Brake Single use packet of Rocksett Forward Controls Design 1210RF: 1210RF Muzzle Brake 5/8x24 QPQ Black