The Troy Industries fixed Rear Battle Sight is a solid sight designed for flat top receivers. The sight is made of hardened T6 aircraft aluminum with stainless steel components. The sight features two apertures, attaches to the rail with a flathead cross-bolt. Please note that this 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. Front sight must be mounted at the same height plane as the rear sight. Railed gas blocks that are lower than receiver height will not zero properly.