When I purchased a 1920s-build home in Philadelphia I was delighted by three original stained-glass exterior windows. I soon realized the single-pane glass and cracked leading allowed air and heat to flow through, yet still I didn’t want to hide them under heavy drapes. With Indow I was able to easily measure, order, and self-install clear insulative panels for about one third the cost of built-in storm windows, and I realized a four degree surface-temperature change in just minutes of installation! I’m seriously considering buying more for temperature and sound proofing of other openings. Great product!