Finally, easy to install window air conditioning support bracket that installs in minutes from the inside and doesn’t require any drilling, tools hardware or fasteners. Just attach the wings and legs, place in the window and the installation is complete. The Top Shelf A/C Bracket features the following: Avoids damage to the structure/window sills, supports up to 200 lbs., rustproofed, two year , Safe, durable and convenient DISCALIMER: The Top Shelf A/C Bracket works with single or double hung windows between 24″ and 38″ wide and does not work in slider, crank out, casement and some wood windows, such as the Anderson 400 series. It will also not work with slide out A/C units. The Top Shelf A/C Bracket needs 10” of clearance below the window. It also requires a minimum wall thickness of 6″ and maximum wall thickness of 12″. The dimension is taken from the inside lower window frame to the exterior sill or ledge if one exists. Always measure the window you intend to use to verify the Top Shelf A/C Bracket will accommodate your window. For further clarification, send photos of your window (open) to the Top Shelf website for review.