Champion RG4HC (309) Copper Plus Replacement Spark Plug, (Pack of 1) 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, Powersport, Small Engine