To install your Trijicon RMR red dot sight, first remove the rear sight from your firearm and replace it with the EGW mount. The mount can be removed and the rear sight reinstalled at any time. All necessary mounting hardware is included. The EGW adapter plate facilitates the installation of a Trijicon RMR red-dot sight on a Sig Sauer M17 by substituting the existing rear sight The package includes mounting hardware, and installation is simple, necessitating a 5/64 inches Allen wrench for the included screws The mount is incompatible with the Sig P320 RX, Sig P320 X-Five, and Sig M17 Military Surplus models