Standard spark plugs are the top choice for more automotive, motorcycle, and marine engine manufacturers than any other brand. Built with a unique copper core and an exclusive electrode design, they deliver quick starts, reliable peak performance, and exceptional longevity.. Triple gasket sealing process eliminates gas leakage past the shell. 99% Highly pure alumina silicate insulator. Solid copper core. Corrugated ribs to prevent flash over. Cold rolled threads to prevent damage to cylinder head. Trivalent plating - silver chromate and zinc for corrosion resistance. Sold Individually