The Polymer Flip Up Rear Sight with Windage Adjustment mounts onto a 1913 Picatinny Rail. A flat head screw driver is required to adjust infinite MOA by 0.25 MOA increments. Unlike other backup sights MFT has developed a shroud that shelters the aperture from debris and impact damage when not deployed. Dual peep sight, same plane aperture allows for perfect cowitness. A slim profile allows the sight to sit under most optics.