NGK IX Iridium Series plugs were designed specifically for the performance enthusiast. Fine wire center electrode ensures high durability and a consistently stable spark. Iridium alloy has an extremely high melting point, perfect for today's high-tech, high performance engines. 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