Stoptech Slotted rotors are a direct replacement for your factory WRX & STi rotors, and will work with stock calipers. Slotted rotors help remove debris that forms between the pad and the disc, allowing better contact and more stopping power. The finish on the rotor also helps prevent glazing and improves performance under wet and dry weather conditions. The area of the rotor that doesn't make contact with the pads is also finished with a durable black coating so no corrosion occurs.