This window film is only suitable for clean and smooth glass surface, do not use on rough, uneven, frosted glass or other materials. This window film adopts electrostatic technology, no need for glues. Before applying, you only need to sprinkle enough water on the glass surface. If the pasting is not firm, it may be the reason of insufficient water. You can tear the product off and paste again after watering. While using, be sure to tear off the back film, otherwise it will not be firmly attached. Please note the distinction between front side and back side, be sure to attache the back side (smooth side) to the glass, otherwise it will not be pasted firmly and even fall off.