Champion RJ12C Marine Spark Plug Champion marine spark plugs are quality OEM replacements. The Champion RJ12C 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 592 California Resid