Spark Plug Application Marine Hex Size 5/8 in Thread Size 0.551 in Thread Reach 0.46 in Ground Electrode Quantity 1 Ground Electrode Tip Design Standard Gap Size 0.031 in Resistor Plug Yes Hex Size - Metric 15.88 mm Thread Reach - Metric 11.68 mm Insulator Material Ceramic Manufacturer Heat Range 6 Seat Type Tapered Center Electrode Diameter 0.098 in Ground Electrode Material Nickel Core Center Electrode Material Nickel