A2 style dual aperture fully protected from accidental damage. Thick rugged pivot ears, twice as thick as the competition. A locking detent with double the locking surface, for maximum strength. A lock detent button with stepped down turns, to provide a surface you can grab onto, if your hands are muddy or wet. Made from 6061 aluminum, and mil-spec hard coat anodizing, to stand up to the most extreme conditions. Same style wind age knob as on the standard M-16 .65 moa on the M-4 type rifles. .49 moa on the A-4 type rifles. Package includes allen wrench for installation.