Cuts down draft and sound in our master bedroom! We can finally sleep comfortably. When I walk into the living room, I can tell that our bedroom is much warmer and cozier. Hope it cools the room over the summer, too. And helped us quite a bit with the noise from the street our huge window faces. But our window was so big (about the size of a king-sized mattress) and the window pane was so deep that we had trouble inserting it into place just right. Thought that a deeper window pane would be easier, but actually it trapped a lot of air that had to be let out in order to securely place the insert there. It was about 55 lbs and required at least two people, but really three to place it very well.