The Power design is a slotted only brake rotor.  Slots are lined grooves machined just beneath the surface of the brake disc. 

These lined grooves act as additional pathways to clear the friction surfaces of debris and hot air and gas.  They help to maximize contact between the friction surfaces as well as create friction to attain the most excellent stopping performance.  This is the design that we recommend for occasional track use or heavy duty applications such as hauling or towing.  For optimal performance, pair this design with our semi-metallic brake pads or our extended wear brake pads!