The potentiostatic double gold electrode was developed to measure the free, inorganic chlorine and chlorine dioxide in water. It is used in the treatment of drinking water, bathing water and process water. A fixed potential is set between the measuring and counter electrodes, which are attached to the electrode body as a double-ring gold foil. A reference electrode is integrated as a cassette. An additional supply of salt in the reference electrode ensures a long service life. The measuring device connected to it determines the measuring parameter and the measuring range. The service life of an electrode depends on various operating conditions, such as the salt content (conductivity), the temperature and the degree of contamination. With drinking water quality and a normal ambient temperature (20 °C), the service life is generally 1 to 2 years. If the water temperature rises, the service life of the electrodes is significantly reduced. The electrode has an M12 connection. The thread is a PG 13.5 thread.