1964 1965 1966 1967 1968 1969 1970 1972 1973 Mustang & 1967 1968 1969 1970 1971 1972 1973 Cougar 1" Bore Polished Billet Aluminum Master Cylinders. Very lightweight all aluminum. Has special coating so the bore does not get pitted like cast iron. Easy bolt-on replacement.