The NES model is a conductive-type level monitor for gauging the level or controlling the pumping of conductive fluids. The principle of operation is thus: on application of a low AC voltage across the container wall and switching point, both of which are conductive, current starts flowing when a conductive fluid fills the gap. This current can be made to operate a relay which is in turn connected to a monitor or pump controller, based on the requirement. Thus, for minimum- and maximum-level control, two switching points and two relays are required, and for multiple-level signaling multiple switching points and relays are required. The lack of any moving parts makes it a preferred choice for use with conductive fluids with high viscosity, very low density, or solid precipitates. Either NE-104 or NE-304 (equivalent to 2 NE-104) relays can be used.