NGK “V-Power” racing spark plug, 14mm thread size. These plugs lower ignition system voltage requirements, have greater ignitability and performance over conventional spark plugs. The Trivalent metal plating has superior anti-corrosion and anti-seizing properties. Promotes increased fuel economy and lower emissions. Highly durable against electrical and chemical wear. If you’re unsure of the heat range you need, a colder plug will eventually foul and misfire, but will not damage the engine. A plug that is too hot can cause pre-ignition.