Magpul MBUS Flip-Up Backup Sights 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