This is a box of 4 Champion Copper Plus Resistor spark plugs. These are new old stock and still in the original packaging.

Plug Type: RF9YC

Seat Type: Tapered

Hex Size (Inch): 0.813

Hex Size (MM): 20.65

Thread Size (Inch): 0.709

Thread Size (MM): 18

Thread Reach (Inch): 0.429

Taper Diameter (Inch): 0.37

Installed Height: 2.27

Insulator Projection (Inch): 0.06

Gap (Inch): 0.033-0.038

Gap (MM): 0.84-0.97

Center Electrode Diameter (Inch): 0.1

Center Electrode Material: Nickel Copper Alloy

Ground Electrode Material: Nickel Copper Alloy

Classification: Champion Copper Plus

Resistor Plug: Y