NGK V-Power Spark Plugs for 6630 UR4 6630 UR4 Tune Up Kit Set bx Improved performance over OEM and Standard plugs for high performance operation with a 30,000 mile service life. Advanced V-groove design and high performance Nickel electrode enhances spark development. Economical performance plug for older vehicles. Precision laser-welded electrode construction. Trivalent Metal Plating has superior anti-corrosion and anti-seizing properties.