Safety and security window films are polyester or PET films that are applied to glass and glazing in order to hold them together if the glass is shattered (similar to laminated glass). The main difference between film and laminated glass is that these shatter safe films can be applied to the glass or glazing after manufacture or installation. I.e., these films are retrofit products. These films are used widely all over the world; they can be found on trains, buses, cars, and buildings. The films are adhesive coated to bond them to the glass. The better safety films are smooth-coated, because they have far superior optical clarity.