MAXIMUM PERFORMANCE: Every Copper Spark Plug has a full copper core electrode which provides higher thermal conductivity for better performance in all conditions IMPROVED DURABILITY: All Autolite spark plugs are Leak proof and come with a heat fused internal seal for long lasting durability CONSTRUCTION: These replacement spark plugs have a copper-glass seal which bonds the insulator and the terminal post center electrode together FUEL EFFICIENCY: The Autolite copper automotive replacement spark plug are guaranteed to deliver quick starts, better fuel economy and smooth acceleration AUTOLITE ADVANTAGE: Since 1936, Autolite has been a trusted leader and innovator in spark plug technology. You can count on our copper plugs for performance and value, backed by decades of experience and passion