ALPHA ATLAS ADAPTER 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. SPECIFICATIONS: 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 Nitride Finish Mfg: Rearden Manufacturing Group Llc