The silver cadmium-plated Power Slot rotors look a whole lot better, and they perform as well as they look. When the pad and rotors create friction under braking, gases are generated which can inhibit stopping performance. The slots are machined in to allow these gases to escape, and they also vent the heat generated during friction--which in turn decreases brake fade. Note the right-side designation on the Power Slot piece. The rotors are unidirectional, so pay attention when you're installing them.