Ultima SwitchNew digital technology uses the Mirus field effect detector cells producing micro-electrical fields that detect disruptions caused by water and fluids. Detector cells are totally sealed, are never in contact with the water, will not corrode and are not affected by oil or foreign debris.ULTIMA activates at a 50 mm (2") fluid level and deactivates at a 20 mm (3/4") fluid level. A 3 second delay prevents false starts. ULTIMA switch is rated to handle all Johnson Pump submersible pumps pumps up to 20 amps at 12 or 24 volts.Features:No moving partsTotally sealed solid state electronics and field detectorsNo mercury No exposed sensors eliminate corrosion possibilitiesUnique 3-way switch disables piezo alarm while keeping warning LED litEnvironmentally sensitive