The Ranco Line Voltage Dehumidistat J10-810 is a two wire, surface-mounted on/off switch designed to be installed in line with existing exhaust fans. Dial-control allows you to adjust settings from 20% to 80% relative humidity (8% maximum relative humidity differential). Automatic switch activates according to your room's moisture levels. Pairs well with most exhaust fans, esp. Fantech and Panasonic models. Notes We recommend hiring a professional electrician to perform installation. Is compatible with most electrical set ups, functions best when installed over a doorway and over its own electrical box. Not recommended for use in high humidity climates, such as summer months in Central Texas. In such climates, unit may very well exchange more humidity than it evacuates. Specs Wires "In Parallel" Switch: Single Pole Single Throw Input Power: 120 volts AC, 60 Hz Maximum Load: 7.5 amp at 120 volts AC Dimensions: 3.1" wide x 4.5" high x 1.2" deep Manufacturer: Ranco