Troy Industries Rear Tritium Folding Battle Sight set the world standard for performance and durability. Like all tritium night sights they are powered by a form of hydrogen that emits a continuous light source where using batteries or electricity is not possible. target acquisition is made possible in low or no light conditions. These Troy Battle Sights are 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.