This adapter plate mounts directly to the pistol using Sig Sauer supplied fasteners. The Trijicon RMRcc is then mounted to this adapter using the Trijicon supplied fasteners. Fits SIG Sauer P365XL Pistol Gen 1 (with rear iron in cover plate) Excludes P365 Spectre COMP; all ROMEOZero ELITE models; P365-XMACRO.