Sample: Part no. BKUR6ET-10
With such spark plugs the spark continually jumps over to a different ground electrodes. In doing so, the wear is distributed up to three ground electrodes and the service life is extended.
When there is carbon fouling, the spark discharge jumps between the surface of the insulator and the air gap. This spark discharge burns off the carbon of the insulator to suppress the decline of insulation resistance.