The Lasko 16-inch window fan will keep you cool both day and night. It provides whole-house ventilation with an electrically reversible intake and exhaust motor. Use exhaust during the day to create a refreshing indoor breeze that expels accumulating heat. Use intake at night to draw in the cool evening air. With the Storm Guard feature, the window can be closed behind the fan quickly to keep rain water from blowing into your home. This window fan fits most double-hung, casement, and sliding windows.