I used this for a year and a half, but I'm selling it because I moved and no longer have the window it fit. It's very easy to install, as you just need to tension it. When I bought it, the size was custom-made, and it cost 11,500 yen. Since it was for a D-room, I think it's versatile as a standard window size. Please understand that some light will enter from both sides as shown in the photos, and that it is a used item. Window frame inner dimensions: Width: 520mm Height: 1220mm