NGK standard plugs are constructed for longer life and optimum performance. Trivalent metal plating provides superior anti-corrosion and anti-seizing properties. Corrugated ribs prevent flashover. Pure alumina silicate ceramic insulator, provides superior strength and better heat transfer. Copper core aids in heat removal. Triple seals prevent leakage.
NGK will often, and inconveniently, discontinue non-resistor plugs to be replaced with the "R" resistor type. For older, non-electronic, ignition systems, be sure to use a LOW, or NO, resistor spark plug cap to prevent weak spark.