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 2007 - 2016 BMW 328i, 2008 - 2008 BMW 328xi, 2009 - 2016 BMW 328i xDrive, 2010 - 2015 BMW X1, 2011 - 2011 BMW 325i, 2013 - 2017 BMW 320i, 2013 - 2017 BMW 320i xDrive, 2014 - 2016 BMW 228i, 2014 - 2016 BMW 328i GT xDrive, 2014 - 2016 BMW 428i, 2014 - 2016 BMW 428i xDrive, 2014 - 2017 BMW 328d, 2014 - 2017 BMW 328d xDrive, 2015 - 2015 BMW 220i, 2015 - 2016 BMW 228i xDrive, 2016 - 2016 BMW 428i Gran Coupe, 2016 - 2017 BMW 330i, 2017 - 2017 BMW 230i, 2017 - 2017 BMW 230i xDrive, 2017 - 2017 BMW 330i GT xDrive, 2017 - 2017 BMW 330i xDrive, 2017 - 2017 BMW 430i, 2017 - 2017 BMW 430i Gran Coupe, 2017 - 2017 BMW 430i xDrive, 2017 - 2017 BMW 430i xDrive Gran Coupe