This is the direct thread mount for the SEG12. Our SEG12 uses the standard 1.375-24 main thread at the back of the suppressor allowing for different mounting options. These direct thread chokes use the M22-0.75 external thread. The direct thread choke requires the M22-0.75 M22 Direct Thread Adapter for the back of the SEG12 suppressor, available HERE. Key Features:NO SHELL OR BARREL LENGTH RESTRICTIONS0.730 Choke IDWeight: 1.5oz17-4PH Hardened Stainless with Black Nitride QPQ finish