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 service life This extra process provides better rotor balance and creates a cleaner; more finished looking component; In addition; Rotors are inspected for balance and mill-corrected to a tolerance of less than 2oz 2012 - 2015 BMW 328i, 2012 - 2015 BMW 335i, 2013 - 2013 BMW 328i xDrive, 2013 - 2015 BMW 335i xDrive, 2013 - 2015 BMW ActiveHybrid 3, 2014 - 2015 BMW 328d xDrive, 2014 - 2015 BMW 328i GT xDrive, 2014 - 2015 BMW 335i GT xDrive, 2014 - 2015 BMW 428i, 2014 - 2015 BMW 428i xDrive, 2014 - 2015 BMW 435i, 2014 - 2015 BMW 435i xDrive, 2014 - 2015 BMW M235i, 2014 - 2016 BMW 228i, 2015 - 2015 BMW 435i Gran Coupe, 2015 - 2015 BMW 435i xDrive Gran Coupe, 2015 - 2015 BMW M235i xDrive