The Diamondhead USA Polymer Diamond Rear Sight features the Diamond-shaped aperture and upper housing that is fitted with a NiteBrite photoluminescent insert. Designed for use with AR15s and Modern Sporting Rifles. Made from an advanced Polymer/Composite construction for?strength, light weight & exceptional durability. The NiteBrite Photoluminescent Insert (a low-cost alternative to Tritium) can be charged by natural light or with a flashlight. The sight is spring-loaded and flips up quickly with the push of a button and stays securely in place when deployed or when folded flat. Dual same plane long and short range apertures at exact same height as factory A2 sights. Easy to adjust 0.5MOA windage adjustment.