Product Details: The Denso Nickel U-Groove Spark Plug is designed to provide superior performance and reliability in a variety of automotive applications. Machine rolled threads prevent seizing or cross-threading during installation and removal, while a purified alumina powder insulator provides exceptional strength and thermal conductivity. A copper glass seal bonds the center electrode and insulator for a gas-tight seal and a five-rib insulator prevents flashover and misfiring. Its design increases spark exposure to the air/fuel mixture for improved combustion and performance. It is the perfect choice for reliable and efficient performance. FleetPride is your First Click in Heavy Duty®.