The MAC-3 liquid level gauge is applied in systems of liquid level control and signaling in open or closed tanks, e.g. in alarm signaling of its minimum or maximum level. Controlled liquids may be: regular water, sea water, acids, bases, brines, alcohol, oils, sewage, sludge etc. Gauges meet the requirements of the European Directive 2014/34/UE for equipment in group I, category M1, and group II category 2G. The MAC-3 gauge is a passive element (without an internal source of supply) which consists of a float, a cable and a weight. Inside the hermetically closed float (IP68) an electric switch with a two-way contact is placed.