Warne Mfg 6102M: 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 two different heights based on their needs. All riser mounts that we offer share a robust mounting base, while the top is engineered specially for different red dot styles. Includes a .180\" thick spacer. Height w/o insert .805\" top of rail to top of riser, Height w/insert .985\" top of rail to top of riser.