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. FeaturesA permanent rail mounted alternative to a standard A2 rear sight or carry handleProvides constant access to fixed sights that continuously hold their zeroExtremely durable and reliable providing peace of mindThe most rugged fixed rear sight availableFits all M4, M16, AR15, AR10 variants and other firearms that have a flat top receiver or removable carry handleNoteSight 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.