Rex Silentium Hydrogen-K (6.5mm bore). Short ultra-lightweight titanium suppressor for PRS shooters and hunters. Grade 5 titanium, tubeless design. 5" long, 6.7 oz (without mount), 1.625" OD. 1.375x24 HUB threads. Barrel restrictions: 24" for .300 Norma/RUM, 22" for .300 PRC, 20" for .300 WM, 14.5" for .308/6.5 CM, 11.5" for 5.56, 7" for .300 BLK super, 5" for .300 BLK sub. Limited full-auto rated (keep under 800°F). Includes 5/8x24 direct thread adapter and tube clamp. Note: If this product is reflected as in-stock it means it's either physically in-stock or allocated and available (serial number is assigned) at my distributor