Champion D-21 Spark Plug, 0.023 to 0.028 in Fill Gap, 0.709 in Thread, 7/8 in Hex, For: Lawn and Garden (Pack of 6)

Patented high voltage semi-conductor resistor for maximum EMI suppression. Copper core center electrode reduces engine misfire caused by fouling. Triple seal assembly with upper and lower metal gaskets and sillment seal, eliminates spark plug failure due to heat or mechanically induced stress. Triple-coated shell, Tintac and Ultraseal over zinc plating resist corrosion and spark plug seizure.