Champion RV91MC Marine Spark PlugChampion marine spark plugs are quality OEM replacements. The Champion RV91MC Spark Plug features a copper core electrode that provides increased conductivity and heat control for good overall wear. These marine spark plugs are designed to resist overheating under heavy engine loads. Resists fouling; Superior corrosion resistance; Dependable and proven performance; Increased conductivity and heat control for good overall wear; Champion Spark Plug # 942M