KAC's line of Micro Iron Sights are currently in use by the United States Army, Marine Corps and numerous law enforcement agencies worldwide. This is because they are built to exacting tolerances, maintain their zero under adverse conditions and, when folded, have one of the lowest profile top-rail footprints in the industry. The KAC 600 Meter Micro Rear Sight features a finger-adjustable, rotating drum that enables shooters to engage targets from 200 to 600 meters with both speed and accuracy. Zeroing Tips 300 Meter Rear Sights: Place a target 25 meters down range and fire a 3 round group(s). Adjust the front sight post and rear sight windage knob until the desired point- Mfg: Knights Armament SPECS: Fits - Picatinny rails. Adjustable sights are calibrated for 5.56x45mm NATO cartridge.