Spectra Premium Spectra Ignition Coil C-781 Unit is designed to Original Equipment (OE) fit, form and function requirements accomplished by leveraging our Original Equipment (OE) engine management systems design expertise 100 percent copper base in both primary and secondary windings Windings insulated by high voltage enamel coating Unit is tested for durability through long-cycle thermal shock test (-50 to 300 Degree F), ensuring reliability against extreme vibrations Each new coil is road tested to ensure real world performance and to verify that each design meets our high standards for quality