To protect electronic devices from being impaired or destroyed by overvoltage. For the wiring of inductances connected parallel to the mains (e.g. relays, contactors, fluorescent lamps, transformers, etc.). Eliminates malfunctions in electronic devices, e.g. reactivation (pulsing) of a motion detector. Dimensions: diameter 25 mm, length 35 mm, length of the connecting cable approx. 100 mm.