Magpul Industries, MBUS Back-Up Rear Sight Gen 2, Fits Picatinny Rails, Flip Up, Black Finish

The MBUS (Magpul Back-Up Sight) is a low-cost, color injection molded, folding back-up sight. The dual aperture MBUS Rear Sight is adjustable for windage and fits most 1913 Picatinny rail equipped weapons, but is specifically tailored to the AR15/M16 platform.
Spring loaded flip up sight
Spring-loaded flip up sight easily activated from either side or by pressing the top
Protective wings shield the dual, same plane flip apertures
Detent knob easily and positively adjusts windage
Polymer construction provides light weight and resists abuse
Detent and spring pressure keeps sight in place but allows for unobstructed folding under impact