StopTech Sport Rotors are also available with an optional cryogenic treatment. Although cryogenic treatment is invisible to the naked eye, many fleet customers are sold on its ability to extend the service life of the brake rotor. Deep cryogenic treatment is a one-time process that permanently improves the performance and wear characteristics of metal components, from brake rotors and engine parts to machine tools and gear sets. All new StopTech Sport Rotors may be ordered with cryogenic treatment for an additional fee. Symmetric vane, split-core castings for uniform heat distribution. Black E-Coat anti-corrosive coating protects much better than competitors spray paint. Double disc ground friction surface for optimal performance and serviced life Symmetric vane; split-core castings for uniform heat distribution; Black E-Coat anti-corrosive coating protects much better than competitors spray paint; Double disc ground friction surface for optimal performance and servicde life 2000 - 2003 BMW 540i, 2001 - 2003 BMW 530i