ProMatrix Front and Rear Rotor Kits offer measurable brake performance improvements to racers and enthusiasts using the OE factory brake calipers. Two piece aluminum hat and GT 72 & 32 Curved Vane Spec-37 assemblies are used to provide high temperature durability for the track and high-tech style for the street. Spec-37 rotors are manufactured from a proprietary iron alloy developed to withstand extreme temperatures with the highest possible degree of resistance against distortion, warping, cracking, and wear. The formulation for this alloy is a derivative of technology and materials that were significant in the development of the extreme duty military spec rotors that are manufactured by Wilwood.