A special thread and shell coating ensures quick and easy removal from aluminum heads and resists corrosion.• Gold palladium insert extends life and improves resistance to corrosion • Tapered tip provides better spark exposure to air/fuel mixture and allows the mixture to flow more easily through gap area for maximum combustibility • Fouling resistance is improved with smaller diameter center electrode wire and insulator tip • Copper-cored ground electrode runs cooler for extended life • Anti-seize coating on threads • Each sold separately • 10R12X