Iridium IX Spark Plug by NGK These NGK Iridium IX spark plugs feature an ultra-fine center electrode that’s designed just thick enough to ensure the maximum durability and life of the spark plugs, and just thin enough to create an accurate and consistent spark. They represent the ultimate evolution of spark plug technology and performance. Iridium is significantly stronger than any metal used in spark plugs today. It’s the hardest metal used (in fact, iridium is 6 times harder than platinum), which has allowed NGK engineers to reduce the voltage requirement for a spark. Features Shorty Spark Plug: No Resistor: Yes Manufacturer Heat Range: 8 Electrode Core Material: Copper Electrode Tip Material: Iridium Insulator Type: Non-projected Spark Plug Thread Size: 14mm Spark Plug Reach: 0.750 in. Spark Plug Seat Style: Gasket Wrench Diameter: 13/16 in. Ground Strap Quantity: One Reach, Resistor, Each Applications This item fits many vehicles, please verify fitment for your application What’s In The Box? (1) Spark Plug