Troy Industries Tritium BattleSights are designed to eliminate the poor sight orientation that is typical in twilight. Tritium is a form of hydrogen that emits a continuous light source when batteries or electricity are not available. The front post is centered between two Tritium points of reference to allow proper alignment. Troy Rear Folding Tritium Sights a permanent rail-mounted alternative to a standard A2 sight allow limitless mounting options on all-length rails with a serrated ramp to eliminate glare. 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. Sight is designed to work on same plane rail systems only. Will not work with a railed gas block that is higher or lower than the receiver.