Protect pump from damage due to low water levels; power cord voltage single-phase, 115 volt * Equipped with a piggyback plug/receptacle connecting submersible pump"s electrical cord * Cut-off switch will cut power on submersible pump when the water level in your skimmer drops * As water level returns to normal levels, the switch automatically restores power to the pump * Measures 3.5-inch width by 5-inch height by 1.75-inch depth