The Champion Copper Plus Marine Spark Plugs 956M / QC12PEP (QTY 6) are high-quality spark plugs designed specifically for marine applications. Made with copper material, these spark plugs are durable and reliable for diesel fuel engines. The Champion brand is known for producing reliable ignition system components, making these spark plugs a trusted choice for marine vehicles. With a California Prop 65 Warning for nickel content, these spark plugs are safe and efficient for marine use.