For high performance and increase in stopping ability with a very minimum amount of pedal effort. We have also gone to great measures to ensure that the R4-S compound have the absolute lowest noise and dust levels, far below O.E.M. equipment or any other high performance brake material. This is an amazingly fast stopping brake pad. Great for autocrossing, drivers schools, solo events, and rallys. The R4-S compound is available for virtually any vehicle sold in the US. We also offer the R4-S in pad sizes for competition type calipers that are used under street driven conditions. The Porterfield R4-S compound has become a consistent top performer in the realm of high performance/street brake pads. Perfect for prolonged everyday street use while also being capable of tolerating the most severe use without any fade.