Standard spark plugs are chosen by more automotive, motorcycle and marine engine manufacturers than any other. The unique copper core and exclusive electrode design assure fast starts, peak performance and long life. Triple gasket sealing process eliminates gas leakage past the shell99% Highly pure alumina silicate insulatorSolid copper coreCorrugated ribs to prevent flash overCold rolled threads to prevent damage to cylinder headTrivalent plating - silver chromate and zinc for corrosion resistanceSold in standard packs only