Conventional spark plug with nickel alloy electrodes Copper core center electrode allows for increased conductivity and heat control Thread size: 14mm Hex size: 13/16" (20.6mm) Reach: 9.5mm (3/8") Seat type: gasket Heat range: 19 Resistor: no Center electrode - Type: standard; Material: nickel; Projection: non-projected Ground electrode - Type: J-gap; Material: nickel