NGK (4286) CR8EIA-9 Iridium IX Spark Plug Designed specifically for the performance enthusiast, Iridium IX offers extreme ignitability, improved throttle response and superior anti fouling The 0.6mm laser welded fine Iridium tip ensures high durability and a consistently stable spark and the tapered ground electrode minimizes electrical Quenching Effect Longer insulator nose prevents fouling, the corrugated ribs on insulator prevents flashover, and a triple gasket seal eliminates combustion gas leakage Iridium alloy has extremely high melting point, giving it high durability to heat and electrical wear, perfect for today's high-performance engines Trivalent Metal Plating - superior anti-corrosion and anti-seizing properties