Stop playing around with spark plugs that feature Iridium electrodes, Platinum electrodes, Copper electrodes, fine wire electrodes, split electrodes, ring electrodes or multiple electrodes and get serious with silver electrodes! Silver is the best electrical and thermal conductor of any metal. This makes Nology Silver spark plugs among the best spark plugs in the world. Period! Benefits: Nology Silver Center Electrode, More Spark Power, Deliver the Most Powerful Spark, Increased Horsepower, Cleaner Combustion, Long Lasting, Race Proven Design, and Top Quality Materials Why not Iridium Spark Plugs? Iridium is a super dense material and therefore extremely resistant to wear. That's it! It is a terrible thermal conductor and a bad electrical conductor, so why would anyone use it to make a spark plug center electrode? Since car manufacturers have to guaranty that their engines stay in-tune for up to 100,000 miles, they can only achieve this with ultra dense Iridium or Platinum. Nology Silver spark plugs are especially designed for high-performance engines. Silver is the best electrical and thermal conductor of any metal, which makes it the ultimate material for a spark plug's center electrode. The large diameter silver center electrode increases spark carrying ability and spark power. Silver is extremely resistant to erosion, guaranteeing a virtually unchanged electrode gap for the life of the spark plug. Most Nology Silver spark plugs are without a resistor, perfect for performance enthusiasts who demand the most from their engines. For racing or dependability and efficiency for everyday use, Nology Silver spark plugs deliver the most powerful spark. If you're not using Nology Silver, you're not going as fast as you could be. The part number for this Nology Spark Plug is 150-141-070 and it is size R4YS. Please use the application guide to confirm fitment before purchasing. M14x1.25 - 25 mm reach, Tapered, 16mm Hex (5/8") Non-Resistor