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 rotors life. The addition of heat and moisture eliminates the effectiveness of phosphate finishes resulting in immediate corrosion once installed in the vehicle. Sold seperately and side specific.