The Magpul MBUS rifle sights are specifically made for the AR15/M4 weapon systems to provide iron-sight functionality that you can also fold away when not needed. The flip-up function is set up to work when the electronics on your red dot fail, or you have to take the scope off and engage in a CQB environment. Magpul MBUS flip-up sights were designed with the tactical operators in minds. Magpul engineers spend countless hours learning what it is exactly that the modern day armed professional needs in order to get the job done. Whether you are a private contractor, a tactical operator in LE or the military, you know you can count on Magpul back-up AR15 MBUS flip up sight to get the job done.