Designed specifically for the performance enthusiast. Iridium IX offers extreme ignitability, improved throttle response and superior anti fouling.The fine Iridium tip ensures high durability and a consistently stable spark.Iridium alloy has extremely high melting point, perfect for today's high-tech, high-performance engines."Trivalent Metal Plating" has superior anti-corrosion and anti-seizing properties. Outstanding acceleration, high fuel efficiency and durability. Ultimate design, technology and performance.Iridium IX Spark Plugs are the most technologically advanced high performance plugs available. Featuring a 0.6 mm iridium center electrode tip, they offer superior ignitability without sacrificing durability. The tapered ground electrode increases flame kernel expansion, while the superior heat range design is ideally suited to the demands of high performance environments. Specially designed to meet the needs of serious enthusiasts, Iridium IX Spark Plugs offer outstanding acceleration, high fuel efficiency and long life. When you demand the most from your engine, rely on the proven performance of NGK Iridium IX Spark Plugs.