I bought this to help pull the hot air from above my rv fridge. I installed it under the fridge roof vent on my toyhauler, and since I’m in the desert and have direct sun mist of the time, the fan will work only when I need it - on hot and sunny days. No need for a thermostat or power switch. I’m very pleased with the quality, low/no noise, and ease of installation. I plan on buying several of these for dog houses that I stash in the desert as a place for lost or stray dogs to get out of the sun.