Advanced design, superior sighting and battle-ready toughness define Troy Industries Dioptic Aperture (DOA) Folding Rear with Tritium, a form of hydrogen that emits its own light source, ideal for any low-light shooting situation. 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, Troy BattleSights provide a continuous zero and fold to a profile of .460". 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 300 meters and a second for up to 500 meters. This versatility makes the DOA ideal for military, law enforcement and home defense applications. *Note- 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.