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