NGK CR8EH-9 Spark Plug NGK CR8EH-9 spark plug for various makes and models. Please see Supported Models tab for a list of vehicle applications.NGK traditional plugs are constructed for longer life and optimum performance. Corrugated ribs prevent flashover. NGK uses only the purest alumina silicate in its ceramic insulator which give all NGK plugs greater strength and better heat transfer. Copper cored and triple sealed to further aid in heat removal and prevent interior leakage. Thread Size: 10mm Reach: 19mm (3/4 inch ) Hex Size: 16mm (5/8 inch) Half Thread Type: 12.7mm (1/2 inch) threaded Gap: 0.9mm (.035 inch) Heat Range: 8 Does not include terminal nut