Troy Fixed M4 Battle Sights Looking for rock solid stability and dead-on accuracy in a fixed sight? Troy Industries Fixed M4 Battle Sights get the job done. Features:- 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- Hardened T6 Aircraft Aluminum with stainless steel components Specifications:- 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- Hardened T6 Aircraft Aluminum with stainless steel components- 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.- Flat Dark Earth.