Magpul Industries USA MBUS Front & Rear Flip Up Backup Sight GEN 2 - 247-248 Made In The USA 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 any MIL-STD-1913 Picatinny/STANAG 4694 receiver rail and provides the same height-over-bore as standard A2 irons NOT for railed gas Blocks