Centric premium rotors utilize an Electrocoating finish that provides long lasting corrosion protection. E-coating is a superior electro-statically applied finish designed to withstand 400 hours of salt water exposure without rusting. Phosphate finishes utilized by other manufacturers provide only minimal protection from the elements; these finishes are generally only effective for the shipping and storage portion of a rotor’s life. The addition of heat and moisture eliminates the effectiveness of phosphate finishes resulting in immediate corrosion once installed in the vehicle. 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 2000 - 2003 BMW 540i, 2001 - 2003 BMW 530i