Spark Plug Application Automotive Hex Size 5/8 in Thread Size 0.551 in Thread Reach 0.75 in Ground Electrode Quantity 1 Ground Electrode Tip Design Standard Gap Size 0.016 in Resistor Plug Yes Hex Size - Metric 15.88 mm Thread Reach - Metric 19.05 mm Insulator Material Ceramic Manufacturer Heat Range 7 Seat Type Flat Center Electrode Diameter 0.023 in Ground Electrode Material Platinum Core Center Electrode Material Iridium