Mirus field effect cell detects disruptions caused by water & fluids. Totally sealed cells never in contact with water will not corrode & are not affected by oil or foreign debris. No moving parts no mercury no exposed sensors. Eliminates corrosion. Environmentally sensitive. Activates at 2'' fluid level deactivates at 3/4'' fluid level. 8-second delay prevents false starts. Handles pumps up to 20 amps 12V or 24V. Made in USA