The XS Shot Rail for the Mossberg 500, 590, 930 Shotgun offers excellent features. Anodized aluminum construction is compatible with weaver or picatinny rings, and drop on installation (if holes are drilled and tapped into receiver). The ring rear sight is precision machined from steel proof steel with elevation and windage adjustment. The banded standard dot tritium front sight provides high visibility in all lighting conditions. FeaturesWindage and elevation adjustable Ghost-Ring rear sight.Rear Sight wings for added protection in rugged environments.Easy install/no gunsmithing Banded Standard Dot Tritium front sight for Mossberg shotguns that don't have a front sight base.Does not fit on heavy barrels; will only with on barrel with diameter 0.840" - 0.860"