Upgrade your engine's ignition performance with the Genuine NGK Iridium IX CR9EIX spark plugs. 4 x Genuine NGK Iridium IX CR9EIX Spark Plugs (NGK 3521). Why Choose NGK Iridium IX?. Tapered Cut Ground Electrode: Reduces electrical quenching, allowing more spark energy to reach the fuel mixture for a more complete combustion.
