Autolite Copper Core spark plugs are designed to give you good fuel economy, smooth acceleration and quick starts with your engine. By having a full copper core ensures that better performance is achieved in all driving conditions. By having a copper-glass seals bonds as insulators and the terminal post centre electrode together, this assures that full required voltage at spark gap and that the seal is gas tight, meaning 100% leak proof. The plug also has a multi-rib insulator which reduces the danger of “flash-over” and the one-piece terminal design add strength.