The MBUS (Magpul Back-Up Sight) is a low-cost, color injection molded, folding back-up sight. The MBUS Front Sight is adjustable for elevation and fits most 1913 Picatinny-railed hand guards. Clamps to most any MIL-STD-1913 Picatinny/STANAG 4694 railed hand guard and provides the same height-over-bore as standard A2 irons. Protective wings shield the spring-locking A2 front sight post. Elevation adjustment tool included, but most aftermarket A2 front sight adjustment tools may be used as well. Weight, with hardware: 1.2 ounces. Height above rail, stowed: ~0.51 inch. Length, stowed: 2.6 inch. Length, deployed: 1.5 inch. Elevation Adjustment: ~1.6 MOA (1.886 inch/100 meter) per click with a 14.5" sight radius. ~1.2 MOA (1.367 inch/100 meter) per click with a 20" sight radius. NOTE: Cannot be mounted to a railed gas block due to excess heat issues. Front MBUS must be mounted to a railed fore end on the same plane as the receiver rail. Because of this the sight is also not compatible with MOE Hand Guards. Made in U.S.A..