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, 25° per side and 0.117" deep Colt Gold Cup- Designed to fit Gold Cup with Eliason rear sight EAA Adjustable- Designed to fit EAA Witness with adjustable Super Sight FN FNH- Designed to fit the FN FNH or FNS H&K HK45- Designed to fit the H&K VP9, HK P30, P30L, HK45, HK 45C Kimber Adjustable- Designed to fit Kimber 1911 with adjustable rear sight Kimber Fixed- Designed to fit Kimber 1911 with fixed rear sight Ruger Auto- Designed to fit Ruger MK I, MK II, MK III, MK IV, P85, P89, P90-95, P97 S&W M&P- Will work with 9mm, 45 ACP, and .22 M&P models Sig P20-229- Will NOT fit on the P220 Dark Elite or the P220 Elite 10mm Springfield XD- Will NOT work with Springfield XDM pistols with the adjustable rear sights DISCLAIMER: This product is not manufactured, authorized, endorsed, or warranted by GLOCK. GLOCK does not warrant or represent that this product is compatible with GLOCK pistols.