Sunbeam SWF4300 Twin Window Fan with Electronic Thermostat Slim twin window fan fits most double-hung and slider windows Independently reversible blades for air intake, exhaust, or exchange 3 speeds; electronic one-touch thermostat and LED display panel Adjustable extender screen and bonus extender panel included Measures 24-1/2 by 4 by 11-4/5 inches; 3-year limited warranty