These Autolite copper core spark plugs feature a cold-formed steel shell with precision-rolled threads, a full copper core electrode to provide better performance, and a one-piece terminal post to add strength. Autolite copper core spark plugs use a copper-glass seal that bonds the insulator and terminal post center electrode together. This ensures full voltage at the spark gap and a 100 percent leakproof, gas-tight seal. Autolite features an extensive application guide to cover just about everything with an internal combustion engine. Keep your engine running smoothly and reliably, simply by switching to some new Autolite copper core spark plugs.