NGK Iridium Spark Plugs 6994 (IZFR6K11) - http://amzn.to/2fCEsp3 NGK (6994) Laser Iridium Spark Plug Designed to operate over a much wider heat range than ordinary plugs Resists carbon buildup and pre-ignition High alumina ceramics for better heat transfer and electrical insulation Solid copper core and nickel tipped electrode provide a longer plus life Patented triple gasket sealing process eliminates the possibility of combustion gas leakage Laser welded Iridium center electrode tip ensures high durability and greater spark Platinum disc welded to backside of ground electrode provides long life Longer insulator nose prevents fouling, Corrugated ribs on insulator prevents flashover, and the triple gasket seal eliminates combustion gas leakage Faster starts and quicker acceleration Better fuel economy and lower emissions, Trivalent Metal Plating for superior anti-corrosion and anti-seizing