This Fan-Tastic Vent is an investment that will ensure comfort by providing immediate air exchange with minimal 12 V power consumption. Fresh, clean outside air can be yours without generators, air conditioners, or engines operating. This model fan has 14 fixed manual speeds or automatic variable speeds, a reverse switch sets the fan blade direction (out-exhaust or in-intake), a rain sensor with on/off switch with automatic dome open/close switch. A built in thermostat maintains your desired comfort level.