Instantaneous fluctuation and harmonics filter, Pro.Fi Filter Single -phase (input / output) filter. It extends the operational life of your equipment by reducing the instantaneous fluctuations in the mains, which can damage or stop electrical and electronic devices or other sensitive equipment. This particular the Pro.Fi filter makes indirect voltage stabilization. It reduces, the instantaneous voltage fluctuations by eight times as well as reduces the harmonics of the network by 50%. Harmonics are largely responsible for failures in electronic devices and sensitive equipment. They are centrally located in any single-phase installation. Their power ranges from 15 to 63 A.