EBC Rear | BSD Rotors (280x10mm) | E85 Z4 2.5iEBC BSD brake discs are corrosion proof with silent braking EBC Brakes range of BSD brake disc rotors feature a lifetime corrosion proof protection with a special thermic black coating. They are made from discalloy and feature bi directional venting to provide better cooling and self cleaning. The specifically designed blade slot helps to remove hot gases efficiently away from the braking zone. This works much more effectively than uni directional