The Avalon high velocity 9" window fan with thermostat and max cool technology is a highly innovative window fan. The fan can be used as an intake fan or an exhaust fan. There are 2 expandable side panels allowing the perfect fit to any window frame up to 37 inches wide. Each side panel can extend up to 6.5 inches. There are also 2 removable legs to use the fan while standing on its own. There is a built-in thermostat with LED indicator lights to keep the fan at a comfortable setting. Each of the two 9" fan heads has its own independent durable copper motor. The dimensions are 24 x 12 x 4 inches. This is an energy Saving device and is ETL approved for the utmost safety.