NGK Multi-Ground spark plugs improve ignition capabilities and are less sensitive to increased voltage requirements do to gap growth. These plugs are designed to meet specific manufacturers ignition requirements. The Multi-Ground plugs have all the same features of NGK's standard plugs including corrugated ribs to prevent flashover. NGK Multi-Ground spark plugs are designed for special motorcycle applications for special ignition demands. Specifications: Shorty Spark Plug: No Resistor: Yes Manufacturer Heat Range: 7 Electrode Tip Material: Nickel alloy Electrode Core Material: Copper Spark Plug Thread Size: 14mm Spark Plug Reach: 19mm Spark Plug Seat Style: Gasket Wrench Diameter: 5/8 in. Ground Strap Quantity: Three Quantity: Set of 4. What's in the box Set Of 4 Spark Plugs