The Warne Picatinny Modular Red Dot Riser mount was designed to offer easy height adjustments with the included spacer to fit red dot optics that use a picatinny attachment and require a riser for use on an MSR. Since picatinny mounted red dots can vary in height this mount allows the user to select 2 different heights based on their needs. All riser mounts that we offer share a robust mounting base while the top is engineered specifically for different red dot styles. - Height w/o insert .805 top of rail to top of riser - Height w/insert .985 top of rail to top of riser - All risers include a .180 thick spacer - Designed and MADE IN USA