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, but is specifically tailored to the AR15/M16 platform. Made in U.S.A. Spring loaded, folding back-up sight. Positive detent locks front sight post.. Lightweight reinforced polymer construction. Adjustment tool & mounting hardware included Made in the USA!