Spectra Premium Spectra Ignition Coil C-846 Unit is designed to Original Equipment (OE) fit, form and function requirements accomplished by leveraging Spectra Premium's OE engine management systems design expertise 100% 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 DegreeF), ensuring reliability against extreme vibrations Each new coil is road tested to ensure real world performance and to verify that each design meets Spectra Premium's high standards for quality