Rule Automatic Bilge Pump Switch ECO-Switch. Featuring a non-mercury design the pump operates with simple air pressure. As water rises in the bilge air rises in the air tube that is attached to switch. This air pressure activates the switch which controls your pump. There are no moving internal parts all wiring is out of the water and there are no submerged electrical connections at all. Offering complete reliability and outstanding performance the Rule ECO-Switch offers a viable alternative to traditional float switches. Specifications for Rule ECO-Switch Automatic Bilge Pump Switch: Manufacturer: Rule Color: Black Voltage: 12 volts Features of Rule ECO-Switch Automatic Bilge Pump Switch Volts: 12v Package Contents: Rule ECO-Switch Automatic Bilge Pump Switch Rule 39: Automatic Bilge Pump Switch ECO-Switch