This 45 Degree angled Front & rear sight is for use with any standard AR-15 and locks positively in the up position with ball bearing pivot detent. It has a low profile and is constructed of black anodized aluminum. The set mounts to standard Mil-Spec 1913 Picatinny rails. Flip up standard A2 Front Post 0.02". Flip up A2 Dual aperture rear peep sight, Small Aperture: 0.070", Large Aperture: 0.200".