Bosch (4449) HGR9BQP Platinum + 4 Spark Plug, (Pack of 1) Revolutionary surface air gap firing technology featuring four yttrium-enhanced ground electrodes delivers the longest, most powerful spark for ultimate engine performance Four yttrium-enhanced ground electrodes provide optimum access to the air/fuel mixture for the most efficient combustion, plus the yttrium alloy ground electrodes reduce gap wear and oxidation for extended performance life Electrode gap is factory set to provide ease of installation - never requires adjustment Never requires gapping, the electrode gap is factory-set and never requires adjustment Provides ease of installation - never requires adjustment