Our windows are large wood casement windows with divided lites about 100 years old. They are beautiful but are single-glazed and drafty--we needed to replace them. Our city has a law that mandates replacement windows that can be seen from the street be the exact same look and materials as the original. Replacing like for like would have been VERY expensive. I found Indows while researching online for a reasonably priced alternative. With the new inserts, the original windows did not need to be replaced and we got the approximate equivalent of double glazed windows for sound as well as heat!