Champion Spark Plugs 401 Spark Plug Rs12Yc Ea.Boxed Champion Copper Core Center Electrode: Allows for accurate control of heat range for longer life Maximum Corrosion Resistance: Thanks to a Patented Ultraseal coated shell Dependable and Durable: Built to ISO and SAE standards for proven performance Maximum EMI & RFI Suppression: Patented SAC-9 semi-conductor resistor for ultimate suppression Compatible with the Following Applications: Automotive, Commercial, Small Engine, Marine