non-woven fabric, the seal blocks hot air from entering through your window and keeps cool air inside Ideal-for those who use portable air conditioners to cool their homes or offices Perfect for top hung window, tilted window, and casement window, and remove without leaving-residue Enjoy a comfortable living-space without spending a on electricity bills and stay cool all long seal is only suitable for commonly-used tilting window or wings It is suitable for window types that open to the left or window that open to the right, bottom hung window, or skylights (not sliding window or doors) But unable to use it on a left and right sliding window or door