Triple-gasket sealing process. Consistent performance. Plug of choice in millions of vehicles. NGK is the world's largest supplier of OEM spark plugs. Tolerances are so close that the margin for error is near zero. Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. It is for this reason that most racing plugs are non-resistor types. However, in most automotive applications, a resistor plug is required for proper vehicle operation. Use of non-resistor plugs in vehicles that call for a resistor type can result in rough idling, high-rpm misfire, and abnormal combustion.