One-way window film is designed by compressing an ultra-thin layer of reflective metallic material between an adhesive bottom layer and a protective top layer. In some cases, one-way film is characterized by having “half-silvered” properties, which means the ultra-thin metal layer is composed of reflective particles. This microscopic metallic layer is so thin that there are only half as many particles compared to that of regular mirrors. The mirror effect created by one-way window films occurs when natural sunlight reflects off the glass it’s applied to. The more outside light there is, and the darker and more reflective the metal layer is, the greater the mirror effect will be.