Wilwood's new Mini Spring rotor are specifically designed for Keizer hubs with 5 x 2.38" mount circle and precision CNC machined from high strength alloy plate. Heat treated, anodized, drilled and scalloped, the full symmetrical machining provides perfect balance and flatness. You get smooth engagement and a consistent full pedal from the low knock-back characteristics of this design. A durable black anodized finish prevents corrosion and simplifies the visual inspection of the contact faces. The best results are always achieved using Purple compound brake pads with these rotors.