Description Reviews SP Performance Slotted Rotors for all R50, R52, R53, MINI Cooper S and S (non JCW Bake option). These high quality rotors are provided with a gray ZRC coating. It provides long-lasting protection against corrosion in the most hostile salt-water environments. After being applied, ZRC provides the highest level of galvanic protection. The film of ZRC is conductive. After the coating heats up during use, it bonds permanently to the metal surface. It will not allow the metal to corrode, even when the surface is scratched. Note: Rotors sold as set, with 1 left and 1 right.