Patio doors are beautiful when the weather is good, but can be a major heat loss when winter comes. Installing a 3M Patio Door Insulator Kit will make a huge difference in your home heating costs. The ultra clear film works just like 3M window insulation, helping reduce condensation while not interferring with your view. Available in either indoor or outdoor, the 3M Patio Door Insulator Kit insulates one 6' 8" x 9' patio door and makes a huge difference in the comfort level of your home.