NGK R6601-10 / R660110 / 4017 Racing Spark Plug Genuine NGK ComponentTo withstand the severe conditions that occur in racing engines, NGK Racing Spark Plugs feature electrode materials and configurations as follows: Electrode materials - Many use precious metals such as platinum or gold/palladium for greater durability and lower voltage requirements. Electrode configurations - Fine-wire center electrodes provide better sparking and enhanced ignitability. Fine-wire ground electrodes further improve the ignitability of the plug. Insulator configurations - Special configurations are used for the insulator noses to improve throttle response. If you are unsure as to whether this is the correct part for your vehicle, please don\'t hesitate to contact us. Alternatively please use the cross reference table above.