The Troy Industries Di-Optic Aperture (DOA) is the future of flip-up iron sights; with an advanced design, superior sighting speed, and battle-ready toughness. These sights provide lightning fast target acquisition and are manufactured to exceed military specs. The optically engineered apertures center your eyes instantly and effortlessly providing a clearer target picture than with round apertures. The Troy DOA sights feature two settings, one for up to 300 meters and a second for up to 500 meters. This versatility makes the DOA ideal for military, law enforcement and home defense applications.