The Wilwood Aero4 forged four piston caliper delivers heavy duty stopping power for the road or track. The caliper incorporates race technology into a body design with widespread adaptability. Radial mounting, multiple options for piston volume, and a rotor diameter ranging from 12.88 in to 15.00 in give this caliper the versatility necessary to suit all types of heavy weight braking requirements. The body of Aero series is stress-flow forged from a premium grade aluminum alloy billet. Stress-flow forging realigns the metal's internal grain structure to flow within the contour of the caliper body. This process eliminates the stresses and interruptions to the internal grain structure that occur when machining a straight block billet. The results are a caliper with superior clamping efficiency and ultimate strength against fatigue, stresses, and distortion under load.