Advanced design superior sighting and battle-ready toughness define Troy Industries Dioptic Aperture (DOA) Folding Rear BattleSight. These sights provide lightning fast target acquisition and are manufactured to exceed military specs. Easy to install and deploy Troy BattleSights are machined from hardened aircraft aluminum and finished in Mil-Spec hardcoat anodizing. Positioned at exact factory height. The optically-engineered apertures center your eyes instantly and effortlessly providing a clearer target picture than with round apertures. The sights feature two settings one for up to 200 meters and a second for up to 600 meters. This versatility makes the DOA ideal for military law enforcement and home defense applications. Sight is designed to work on same plane rail systems only. It will not work with a railed gas block that is higher or lower than the receiver but will work with our Gas block Front sights.