Receiver/Amplifier Megabase Cooling Fans with Adjustable Thermostat & Multispeed Control This super low-noise dual-120mm fan unit is designed to sit on your receiver's top air vents. It has a special raised air-chamber base, which covers 145 square inches, and air is drawn out over the entire area of this raised base. The system is temperature controlled, via a built-in thermostat: The fans will not come on until the area under the raised base reaches the temperature you have set. Then you will feel a steady stream of warm air as the fans pull it out of your receiver, creating a vortex of cooling air that is drawn in through the bottom vents. When the temperature of your receiver cools down below the set temperature, the fans shut off automatically. In addition, you control the speed of the fans, with the multi-speed power controller. Recommended fan speeds for this system: The fans (running together) are rated at 13db while moving 50 cubic feet of air per minute at 1/3 speed, or 16db & 72CFM at 1/2 speed. With component cooling, slow (and quiet) are the way to go! Other available speeds: 2/3 speed = 19db/98CFM, 3/4 speed = 22db/110CFM, full speed = 25db/148CFM. The Megabase cooling unit measures 14.5" wide, and 10" deep. It is 1-1/2" tall, and only requires about 1/4 inch of additional space above for airflow.