MBUS 3 Rear Sight by Magpul is a compact spring‑loaded flip‑up iron sight made from impact‑resistant polymer. When stowed it stands only approx. 14 mm high and approx. 35 mm wide. Deployed, it provides standard AR sight height and features ambidextrous push‑button deployment and a rapid‑select dual‑aperture windage adjustment system. Weighs just 30 g including mounting hardware.