Dagger Defense flip up BUIS 45 degree picatinny rail mounted backup iron sights.Picatinny rail mounted BUIS 45 Degree angled Aluminum alloy in black matte finish Spring loaded flip up feature Great back up iron sights for red dot Fits most standard picatinny rail system The Dagger Defense 45 degree angled BUIS backup iron sights for use on standard picatinny rail mounts. A must have accessory for your picatinny rail systems. Has spring loaded, button activated flip up function to give you the extra advantage. Use in combination