NGK Laser Iridium Spark Plugs offer the best combination of performance and longevity. Iridium tipped center electrode provides durability six times harder than platinum. NGK's high-grade pure alumina ceramic and 98% pure copper core prevents the spark plug from overheating while providing reliable starts. Taperedcut ground electrode improves ignitability and reduces quenching 98 pure copper core increases heat dissipation for more reliable starts and prevents spark plug from overheating Highgrade alumina silicate ceramic insulator for superior strength and heat transfer Iridium is six times more durable than platinum