ESO and the Astronomical Observatory of Torino (OATo) are collaborating for development of a Fringe Sensor Unit (FSU) for the Very Large Telescope Interferometer (VLTI, see [1] and references therein): FINITO (Fringe-tracking Instrument of Nice and Torino), derived from the concept demonstrated by a prototype from the Observatoire de la Cote d’Azur. It will be used for stabilisation of the Optical Path Difference (OPD) between telescope beams for the first generation scientific interferometers (AMBER, MIDI, VINCI), providing an improvement of up to five magnitudes in limiting sensitivity, thanks to the integration time increased from a few ten milliseconds up to minutes. Accordingly to current planning, FINITO is the only FSU able to support three-beam observations, allowing closure phase measurements in the near and mid IR range.