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. Weight: 1.22 oz Length Added: 0.350a ^2 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 Alpha Low Profile The Alpha Atlas provides a mount interface for suppressors that use the low profile style adapters with inside diameter threading of 1.125-28, like the Omega 9k. This adapter can be used with Rearden muzzle devices as well as other brands.