Suncourt Flush Fit Smart Register Booster Fan quietly boosts heated or cooled air to a room to improve circulation and comfort. Our new and improved register booster fan features patent pending smart technology, a built-in temperature sensor and works automatically with forced air systems. It has 5 fan speeds with dual fans that pull extra air out of weak registers, boosting airflow by up to 85%. It is a simple, energy efficient and safe solution for rooms that are too hot or too cold. Features: New patent pending self-learning technology turns the register booster on and off with your heating and air conditioning system. No programming necessary! Set-Up in seconds: plug-in, set on register and enjoy improved comfort No seasonal temperature settings necessary! 5 fan speed settings, up to 132 CFM, for maximum control and comfort Includes the Flush Fit Adaptor plate for register sizes: 4" x 12", 6" x 10", and 6" x 12" Can be installed in floor or wall registers. Installing a ceiling register is not recommended Fits flush with the floor or wall for a clean contemporary look