Trusted by more engine manufacturers than any other, standard spark plugs offer unmatched reliability. With a copper core and exclusive electrode design, they deliver faster starts, superior performance, and longer life-keeping your engine running at its best.. 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