Matech is a major supplier and military contractor. This is the same BUIS as used on M4 and M4A1. Adjustable, pre-set ranging, flip-up, aperture sight fits any standard Picatinny rail. New, not surplus.
Current U.S. Army standard-issue backup rear sight for M4 carbines and M16A4 rifles flips up instantly at the touch of your thumb when primary sight fails or tactical situation makes iron sights preferable. Designed in conjunction with Picatinny Arsenal engineering staff and rigorously tested at Fort Benning and Aberdeen Proving Ground for robustness, ease of use, and effective targeting out to 600 meters. Detent-locking lever lets you quickly switch to one of eight range settings: 200, 300, 350, 400, 450, 500, 550, and 600 meters (calibrated for 5.56 NATO). Adjust windage easily with grooved, A2-style windage knob and position markers on the back of the sight for repeatability of settings. Bright, white, laser etched numbers and markers are clearly visible even in low light. Regulates correctly with A2 front sight on any AR-15-style rifle or carbine.