These two piece rotors are used on RR Racing front Stage 3 and 4 brake kits. They are an upgrade to Stage 1 and 2 kits. When we say our race rotors are "race proven" we mean it. Our cast iron rotors are manufactured by Coleman Racing. These are the same rotors as featured on NASCAR Winston Cup cars. Rotors feature a custom slotting pattern, directional cooling vanes, and zinc chromate plating to resist corrosion. Our plating will withstand higher temperatures than common "e-coating" that other manufacturers use. All components in this product are proudly engineered and manufactured here in the United States of America.