Indows seal well and provide an extra layer of thermal comfort. We have done side-by-side comparisons with and without them, and there is much less condensation on the inside of the Indows and on the Martin windows without them. They also work better than gluing plexiglass into extra screen frames because the seal is better. That said, the Indow acquisition and installation does take time. The window measurements take time, removing the protective layer from the Indows takes time, and getting them into the window frames takes a bit of patience. The end result, however, is a perfect fit.