The Leupold Ruger M77 Extension Ring Mount was designed specifically for weapons with an integral mounting system, like the Ruger M77. This ring mount system comes in both 30-milimeter and 1-inch diameters, so you can choose the one that is right for you. Not only is the Leupold Ruger M77 Extension Ring Mount perfectly designed for use with Ruger 77 models, but it is constructed from machined steel to ensure maximum durability. As an added bonus, this ring mount is made to give you the extra height you need to properly mount your rifle scope.