Troy Rear Tritium Folding Sights TRITIUM is 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. - No limited sight orientation due to low light conditions - Front post is centered between two tritium points of reference to allow for proper alignment - Black Note: Sight is designed to work on same plane rail systems only. Will not work with a railed gasblock that is higher or lower than the receiver..