The Air King 9137 Twin Table Window Fan is a versatile fan that can be used during the day or night. It features 7 inch propellers and fits windows with a width of 22-34 inches and a height of 12 inches. The advanced features included with the 9137 include: Intake or Exhaust: Can be set to draw in cool air from the outside or expel out warm air.Versatile Window Compatibility: Fits most window types such as double hung, casement and sliding windows. Two Selectable Speeds: There are two quiet, energy efficient speeds for just the right amount of cooling. Easy Operation: Comes fully assembled for instant cooling upon arrival. Optional snap-on feet are included for floor or table use.