The Comfort Zone CZ319WT 9-inch Twin Portable Window Fan features dual 9-inch fan blades with two speeds (low and high) to generate a brisk breeze or circulate air in a room. It is designed to fit most double-hung and slider windows with auto-locking accordion expanders that adjust between 22-1/4 inches and 33 inches wide. The fan can be manually reversed to operate in intake mode (bringing in fresh, cool air) or exhaust mode (pushing out hot, stale air). The unit is made of durable plastic and includes a removable fabric cover to keep out bugs, dust, debris, and hot air when the fan is not in use. It also features two sturdy, removable feet for convenient tabletop or desk use and an integral carrying handle for portability. The fan operates on 120V and is ETL/US Listed for safety