These are FR500S brake rotor brackets for the FR500S.  They are brand new.  They are dimensionally the same as FR500C with 14″ brakes.  These brackets will mount the Brembo F50 caliper to an S197 2005-2014 Mustang (CALIPER IMAGE INCLUDED FOR REFERENCE ONLY). They will also work to mount Stoptech calipers on a Mustang.  If you used Stoptech calipers, you NEED to use FR500C, FR500S, or Boss S rotor hats.