Standard Nickel. Performance Spark Plugs NGK nickel spark plugs feature a specially designed v-groove center electrode, improving ignitability and reducing quenching. The 98% pure copper core provides increased heat dissipation for more reliable starts and reduced risk of overheating. Cold-rolled threads prevent cross-threading and damage to cylinder heads Trivalent plating eliminates need for anti-seize Premium-grade alumina silicate ceramic *By request/order.