SONTE film works like an ultrathin LCD TV. It consists of a layer of conductive liquid-crystal polymer sandwiched between layers of PET plastic. Users trim the film to the size of the window and smooth it onto the glass. A semipermanent adhesive holds the film in place. Each kit comes with a quarter-size clip, which attaches to a corner of the film and plugs into a Wi-Fi–enabled electrical transformer. Once connected, users can control the panel with either an app or a traditional switch. When on, a current flows through the liquid-crystal layer, adjusting its polarity and turning the panel transparent.