Made from durable, metal-reinforced polymer and are a good option when seeking a quality sight Front sight measures .600" when folded & the rear measures .610" Front sight length is 2-1/4" Designed for 1913 mil-std rails and the front sight is for free float handguards, not to be mounted on gas blocks Rear sight features the same metal dual apertures utilized in the A.R.M.S. #40l under contract with crane naval special warfare center, for both CQB and long range shooting applications Mfg: A.R.M.S.