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. FEATURES: Impact resistant polymer construction provides light weight and resists operational abuse; Spring-loaded flip up sight easily activated from either side or by pressing the top; Detent and spring pressure keeps sight erect but allows for unobstructed folding under impact, etc.; 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.