This is a new old stock set of AP billet, removable bridge, race calipers w/ 4 piston (stainless alloy) differential bore 30mm / 34mm for 300mm-328mm x 28mm-32mm rotors. Part #CP5610. Pad shape PFC #7735, 7736 / AP 5510D43  This set has been race prep'd but never raced. Part of the prep was to machine the caliper bodies to increase the diameter range of the rotors these calipers can use. Very popular road course rear application.