This MAD BUIS was designed for the Naval Surface Warfare Center. For the maximum in utility, this sight features a four sight, rotating aperture disk with the small and large apertures on the same plane. You can now shift from a high accuracy small aperture to a quick acquisition large aperture with a click of the aperture disk. The MAD unit mounts easily to the standard flat top receiver. The MAD sight features full windage adjustment and is finished to military specs. Now equipped with locking detent.