NGK (4339) Standard Spark Plug, Pack of 1 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 Solid copper core for greater spark Longer insulator nose prevents fouling Corrugated ribs on insulator prevents flashover Zinc dipped shell prevents corrosion Triple gasket seal eliminates combustion gas leakage