Tjernlund CBW Automatic Register Booster Fan, Steel, White Installs flush with floor in seconds in any 3"x10" or 4"x10" register boot opening Operates manually or automatically for any season with a built-in, hidden sensor Features Sturdy Steel Construction and Grounded Power Cord Built-in 45 degree turning vanes guide air to the center of the room 20 Watt Low Energy Cross Flow Blower means its whisper quiet--no annoying buzzing like other fans Save energy and wear on your furnace or AC by getting the air to where you really want it.