The Bilge Alert High Water Alarm from Johnson Pumps produces a micro-electrical field using a patented Mirus field effect detector cell. This field detects any disruptions from water or fluids in your bilge pump. The sensor then triggers a 100db piezoelectric alaram LED light on the control panel to inform you of disruption. A built in delay prevents any false starts and the detector is sealed, so it will not corrode or be affected by oil or debris. The Bilge Alert High Water Alarm includes a three-way rocker switch that allows users to test, turn off and arm the alarm.