Wilwood Rotor-SV-GT 72 SPC-37 -LH 14.25 x 1.10 - 12 on 8.75inWilwood's GT 72 Curved Vane 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. Every Spec 37 rotor is precision