The 3 lug interface assembly is an integral 3 lug assembly which adds minimal length to the suppressor. This kit allows for QD mounting of many Griffin suppressors. To view applicable calibers and ratings see individual suppressor product pages. Griffin's 3 lug adapter requires minimal deflection of the spring bushing for installation in some cases negating the need to modify hand stops and grips that come close to the 3 lug adapter. The 9mm kit fits H&K standard 9mm 3 lug adapters as well as Griffin 3 Lug Adapters. US made Barrels from RCM and Michael's Machines comply with these dimensions as well as German HK brand barrels.