This is a red dot slide mount to fit the GSG 1911. It is designed for the Vortex Venom and Viper and other compatible red-dots. If you want a slide mounted red-dot then this is a great way to get up and running without any alteration to your GSG long barrel pistol. The low mass of the mount doesn't interfere with cycling and keeps the sight as close to the barrel as possible.
Other red dot sights such as the Burris FastFire can be made to fit, but will require some "fettling" to achieve a sound fit. We recommend using thread lock (not supplied) when installing this product and tightening screws/bolts to no more than 10 inch pounds.