The Alpha Atlas provides a mount interface for suppressors with inside diameter threading of 1.125-28, like the Rugged Obsidian 9 and Obsidian 45. We do not recommend this on suppressors that use the low profile style adapters, like the Omega 9k. This adapter can be used with Rearden muzzle devices as well as other brands. Weight: 1.22 oz Length Added: 0.350 Threads: 1.125-28 (Silencerco Alpha thread pitch) 17-4 PH H900 Compatible with short Rearden devices (FHD, Mini, SPB, RPB, R2S) Compatible with Q Cherry Bomb and Other Plan B Compatible Muzzle Devices