This is a new Panasonic product, three conrols built into a single wall switch sized unit. The top indicator light shows when the condensation sensor is on. The condensation sensor automatically turns on the exhaust fan when the dew point (point of condensation) is reached. It works in all climates, all seasons. Push the middle button, and the fan stays on for an adjustable 30 seconds to 60 minutes. The bottom button is a manual on/off option. This unit is compatable with all single speed Panasonic fans.