RF probe type level switches use RF Admittance technology to produce switching action when a material level crosses the set point of its sensing probe. Many probe configurations are available. The interface position between two liquids with different dielectric constants can be accurately detected by the switches. The units will even average out a cloudy interface and produce a precise switching action as its position passes the set point. A limitation is that one of the liquids must be nonconductive. They are not sensitive to specific gravity variations. Water/hydrocarbon interfaces produce excellent results. Detecting a liquid interface as it moves down a pipeline is another useful application.