WJ Dennis & Company 21 Window Air Conditioner Cover, Fits 15,00 + BTU Models, 28-Inch W x 20-Inch H x 30-Inch Dia, Grey Helps unit resist mildew and rot For use with a window air conditioner Extend the life of your air conditioner with this reusable cover Fits all extra large window models 28"W x 20"H x 30"D 15,000 and up BTU, Heavy Mil.