The Pro-Hub Tool is required for the Pro-Outer Hub Shaver and the Pro-Wheel Shaver. 1.Ensures accurate rotation by squaring the outer wheel hub to the wheel bore for proper mounting on the Pro-Wheel Mandrel. 2.Improves wheel hub to axle head contact by eliminating flaws on the outer wheel hub. Note:The Pro-Outer Hub Shaver is intended for use on BSA and PineCar wheels. It is not intended for use on wheels by other manufacturers.