Holmes HAWF2041 Dual Blade Window Fan with Comfort Control Thermostat, White

The Holmes Hawf2041 double window fan can exhaust stale, hot air from inside or draw in fresh, cool air from the outside. Or, because of the draw-in and exhaust-out settings for each fan independently, it can do both simultaneously. With a thermostat that controls the on/off settings on the fan according to your preset temperature level, plus three speeds for each fan, the unit adjusts flawlessly to your environment. Designed to fit double-hung, vertical, and casement windows, the fan comes with a built-in 7-inch extender and two separate 3-inch extenders, letting you fit it in windows from 24 to 37 inches wide. The fans have six blades and measure 8-1/2 inches in diameter.