SPARK PLUG LMAR9D-J 1633 Home Automotive Spark Plugs Special Motorcycle Plug Multi-Ground Corrugated Ribs Copper Core DESCRIPTION SPECS REVIEWS FITMENT Multi-Ground Electrodes Improve Ignition Capabilities and are Less Sensitive to Increased Voltage Requirements Due to Gap Growth. Designed to Specific Manufacturer Ignition Requirements, NGK's Multi-Ground Plugs Maintain All the Features of Their Standard Plugs, Including: Corrugated Ribs to Prevent Flashover Pure Alumina Silicate Ceramic Insulator, Providing Superior Strength and Better Heat Transfer Copper Core to Aid in Heat Removal Triple Seals to Prevent Leakage