NGK nickel spark plugs feature a specially designed v-groove center electrode, improving ignitability and reducing quenching. The 98% pure copper core delivers increased heat dissipation for more reliable starts and reduced risk of overheating. High-grade alumina silicate ceramic Creates a stronger insulator to reduce dielectric punchthrough (caused by spark exiting through the side of the ceramic). Cold rolled threads Prevents cross-threading and damage to cylinder heads. 98% pure copper core Increased heat dissipation for reliable starts, prevents spark plug overheating. Trivalent metal plating No anti-seize required. Ground electrode Designed to reduce quenching effect, resulting in better ignition performance.