These Champion Spark Plugs deliver a consistently focused spark with minimum RF interference.Plugs you can count on, the Champion Spark Plugs we offer boast all the features that make Champion an industry leader. Plugs feature a triple-coated shell for excellent corrosion resistance, and a triple seal assembly that is the strongest in the industry. Precision rolled threads conform to all manufacturers specifications.Key FeaturesTriple-coated shell offers excellent corrosion resistanceTriple-seal assembly is strongest in industryPrecision-rolled threads conform to all manufacturers specs"Q" and "R" plug types offer Radio Frequency Interference (RFI) suppression to protect sensitive electronicsAvailable for inboard, I/O and outboard motors and personal watercraftMade in U.S.A.RFI SuppressorsThe Champion Spark Plugs that we offer that begin with the letters "Q" and "R" include RFI suppression, so they wont affect your radio or navigation equipment. R-type plugs include Champion's SAC-9 RFI suppressor, which is a resistor made of strontium carbonate, aluminum oxide and copper oxide powders.Q-type plugs limit RFI with an inductive suppressor, which consists of awire wound inductive coil that reduces RFI without negatively affecting ignition performance. Q-type suppressor plugs are specified for most Evinrude and Johnson outboard engines with CD ignition. Usage of non-Q types (or standard resistor plugs) can actually cause engine misfire and a loss in performance.Plug SelectionTo ensure optimum performance please consult your owner's manual to determine the correct spark plug for your engine.