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. NGK's new Iridium IX is the personification of these qualities and takes premium performance spark plugs to a new level. A level that is expected from the world leader in spark plugs.