The present invention relates to a spark plug extension body connecting an ignition coil with a spark plug for a spark ignited internal combustion engine, as well as a method for providing such a spark plug extension body for reduction of partial electrical discharges in the spark plug extension body. In conventional spark plug extensions are coil springs used as electrical conductor against the spark plug terminal and/or ignition coil terminal. These coil springs cause Corona effects and short circuiting requiring replacement of the spark plug extension. With the invention the entire electrical conductor (CRu, 64, CRL) is in a rod like form and at least both ends (CRu, CRL) of the electrical conductor (CRu, 64, CRL) are made as a monolith in a flexible and electrically conducting polymeric material, preferably electrically conducting rubber.