The ProMag multiple aperture rear sight is a low profile flip-up rear sight with 5 range settings. The low profile design will clear most optic mounts when folded, but is still easily deployed. The sight features an a2-style windage knob that can be adjusted without tools, and apertures for 0-200, 300, 400, 500, and 600 yards. The yardage setting is visible to the shooter through a small window below the aperture. This sight is optimized for 55 to 62 grain 5.56x45mm NATO ammunition, out of a 16" barrel. Other types of ammunition may not align with the yardages marked on the sight. The sight is secured to the picatinny rail with a knurled, slotted cross bolt. The sight is constructed of T-6 aircraft aluminum and anodized with a type-3 hard coat.