Openable Invisible Grille is One kind of Invisible Grille. Casement and Sliding invisible grille are the other two. This design lets you open your window to the left or right, just like your regular windows, so you can get the most light and air into your room. Most of the time, Invisible Grille are put on windows that need access to the outside, like the AC compressor or the laundry ... https://elelaurels.com/