Simply remove the rear sight on your gun and replace it with the EGW mount in order to mount your Vortex Razor or C-More RTS/STS red-dot sight. You can take the mount off and replace your rear sight at any time.No alterations are required and mounting hardware is included. Fit Notes:1911- Designed for the standard GI dovetail cut that measures 0.347" wide, 25Adeg per side and 0.117" deepColt Gold Cup- Designed to fit Gold Cup with Eliason rear sightEAA Adjustable- Designed to fit EAA Witness with adjustable Super SightFN FNH- Designed to fit the FN FNH or FNSH&K HK45- Designed to fit the H&K VP9, HK P30, P30L, HK45, HK 45CKimber Adjustable- Designed to fit Kimber 1911 with adjustable rear sightKimber Fixed- Designed to fit Kimber 1911 with fixed rear sightRuger Auto- Designed to fit Ruger MK I, MK II, MK III, MK IV, P85, P89, P90-95, P97S&W M&P- Will work with 9mm, 45 ACP, and .22 M&P modelsSig P20-229- Will NOT fit on the P220 Dark Elite or the P220 Elite 10mmSpringfiel...