Autolite Copper Core Spark Plugs deliver quick starts, good fuel economy, and smooth acceleration. The copper-glass seal bonds insulator and terminal post center electrode together to ensure full required voltage at spark gap, creating a gas-tight seal that is 100 percent leak-proof. Copper Core spark plugs feature a cold-formed steel shell and precision rolled threads, and a one-piece terminal post that adds strength. The multi-rib insulator reduces the danger of "flash-over" to prevent misfires, and the resistor reduces radio frequency interference (RFI) and electrode erosion. The full copper core electrode provides better performance in all conditions. Autolite Copper Core plugs are your industry standard. 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 copperglass 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