The Indows product comes in several grades which are mostly a difference in thickness. They are designed to essentially be a "third pane" by leaving an air gap between the inside surface of your house window and the Indow insert that is pressed into place by a perimeter of soft silicone type gasket. The Indows are not sound proof, but are rather draft and noise reduction inserts. The Indows are straightforward to insert and remove, but somewhat fiddly in that they fit snuggly--which is necessary for the best seal. You cannot open your windows with the Indows in place, so if you want open windows part of the year, you'll need to remove the Indows and store them. If you plan on having open windows part of the year, I recommend you get their storage covers as the Indows are plastic and can scratch.
The Indows do noticeably reduce noise, and without doubt my...