Spark Plugs, Iron XLPlugs have a unique look with their black ceramic body and bold red logo/script Insulator is made of 95% pure alumina; features strong resistance to heat shock and superior insulation Multi-rib design of insulator eliminates flashover Nickel-plated housing prevents oxidation and corrosion Multilayer gaskets and heat-crimping process ensure a leak-free, gas-tight fit Copper core electrode prevents oxidation and corrosion and has good electrical and heat conductivity for long spark plug service life