Matech OGU83 BUIS (Back Up Iron Sight) ranging rear sight for AR-15, M16a4 M4, M4a1 and other weapons. Sight is military issue, take off from upgraded M16a4 or M4 – M4a1 US Gov't/Military issue weapon, in lightly used, excellent condition. Made of steel, black finish, fits any MIL-STD-1913 rail, Picatinny rail. Back up sight when removing or using without handle, can be used and co-witness with Eotech or other prism and red dot sights, has flip up aperture. I have multiples, selling for $70.00 each, cash only FTF Plano, Texas or, will ship, buyer pays shipping costs and only USPS Postal money order accepted, no exceptions. Sold as shown, sold as is.