AV Receiver Airchamber Base cooling fans with thermoswitch & mult-speed control This dual-80mm fan unit is designed sit on your component's top air vents. It has a special raised air-chamber base, which covers over 80 square inches (11.25" x 7") of the vents. Air is pulled from your component over the full area of this raised air-chamber base. The system is controlled by a built-in thermoswitch, which turns the fans on and off at approximately 82F. You control the speed of the fans, with the multi-speed power controller. Even at medium speeds settings, the fans will replace a volume of air equal to that of most components several times per minute. Recommended fan speeds for this system: The two fans (running together) are rated at 13db while moving 31 cubic feet of air per minute at 1/2 speed, or 16db & 41CFM at 2/3 speed. With component cooling, slow (and quiet) are the way to go! Other available speeds: 1/4 speed = 10db/16CFM, 3/4 speed = 19db/46CFM, full speed = 22db/62CFM. The Dual-80mm Airchamber base cooling unit measures 11-1/4 inches wide and 7 inches deep. It is 1-1/2" tall, and only requires about 1/4" of additional space for airflow.