Heavy-duty yttrium enhanced nickel-copper center electrode ensures superior reliability and durability for up to 50% longer performance life vs. standard copper plugs Copper core provides broader heat range to resist pre-ignition and deposit build-up Nickel-plated rolled threads provide superior resistance to corrosion and do not require anti-seize - saving time Angled, ribbed insulator design prevents misfire due to flash-over Metal glass fused resistor maximizes interference suppression