ELECTROHOME 8000 BTU AIR CONDITIONER fits in any opening that is at least ( can be larger ) 18.5" W and 13" H . If the opening is larger there are expanding sections that block off the extra space to keep dust, insects rain and heat out .These are included but not shown in the pics. This works great , I replaced it with central air so it is no longer needed. Electrohome is an Ontario manufacturing company . I recently priced a smaller , made in China unit for $250 plus taxes & enviro , so feel my price is very reasonable.