Copper Core Spark Plugs deliver quick starts, improved fuel economy, and smooth acceleration. The copper-glass seal bonded insulator, terminal post, and center electrode ensure a tight seal that is 100 percent leak-proof, and the full copper core electrode improves heat transfer and optimizes plug life. Copper Core Spark Plugs feature high alumina ceramic for high dielectric strength, and a steel shell for installation robustness. The multi-rib insulator reduces the danger of "flash over" to prevent misfires, and the copper core center electrode provides higher thermal conductivity. These spark plugs are engineered with a high nickel alloy center and ground electrode for extended life. Autolite has over 100 years of engineering experience and has sold over 11 billion plugs. Since its inception, the Autolite brand has provided the automotive aftermarket and Original Equipment manufacturers the highest quality ignition products. Designed and engineered in the USA.