Autolite Iridium XP Spark Plug are one of the most advanced spark plugs on the market. The iridium-enhanced .6 mm finewire design and proprietary platinum sidewire technology provide better a more focused ignition for better overall ignitability and optimum performance. They also feature a nickel plated shell to prevent corrosion. Autolite Iridium XP Spark Plugs are designed for better overall durability with no gap erosion so engine performance stays consistent.