Spark Plug Code: RJ19LM Copper Plus spark plug has a copper core center electrode that allows for accurate control of heat range optimizing performance and longevity of the spark plug. Patented SAC-9 semi-conductor resistor for maximum and suppression. Patented Ultraseal coated shell for rust prevention. Plug Type: RJ19LM. Seat Type: Gasket. Hex Size (Inch): 0.813. Hex Size (MM): 20.65. Thread Size (Inch): 0.551. Thread Size (MM): 14. Thread Reach (Inch): 0.375. Taper Diameter (Inch): 0.25. Installed Height: 1.9. Gap (Inch): 0.0295-0.0335. Gap (MM): 0.75-0.85. Center Electrode Diameter (Inch): 0.085. Center Electrode Material: Nickel Copper Alloy. Ground Electrode Material: Nickel Copper Alloy. Classification: Champion Copper Plus. Resistor Plug: Y