XS Sight Systems AR-2004-9 XS AR - CSAT A2 Same Plane GRA
Designed by Paul Howe to allow the operator to accurately engage targets from 7 yds. to 100 yds. without moving hands to flip sights or have a second set of sights. The notch on top is used for targets at 7 yds. with a sight picture similar to pistol sights. The aperture is used for targets at greater distances and is used as a normal AR-15 rear sight.