This Denso W16EXR-U is a standard spark plug that fits thousands of makes and models of vehicles. Its U-groove tip allows the spark to fill the shape of the groove for a larger, hotter flash front to eliminate excessive fouling and erratic starts caused by poor fuel mixtures. The plug's five rib design prevents flashover and reduces voltage loss, and the insulator is made of highly purified alumina powder for strength and thermal conductivity at high temperatures. A mixture of copper and glass powder bonds the center electrode and insulator together for a gas-tight seal, and the electrode has a copper core for maximum thermal conductivity and increased operating range.Specifications