Bosch Fusion Spark Plugs, 4516: * Fused iridium and platinum center electrode * Centered into an extended insulator nose reaches self-cleaning temperature only seconds after starting * Improved resistance to fouling, reliable starts * Provides exceptional wear resistance to meet OE specifications for long life iridium spark plugs * Revolutionary surface air gap firing technology * Bosch"s unique 4-ground electrode design that delivers the most powerful spark for the most efficient combustion and optimum horsepower without increasing the voltage requirement * 4 yttrium-enhanced ground electrodes resists spark plug wear and oxidation for exceptional performance life * Factory pre-set gaps provide ease of installation which never requires adjustment