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., it is a retrofit product. These films are used widely all over the world; they can be found on trains, buses, cars, and buildings.
Safety and security films are used where there is a potential for injury from broken glass (such as glass doors or overhead glazing). These films can be applied to toughened, annealed, or laminated glass. They are available in various thicknesses, from 100 micrometer (or 4 mils minimum 2 ply) through to 525 micrometers (21 mils). The film thickness is selected for level of protection desired and the dimensions of the glass pane. Manufacturers recommend 100 micrometer film (2 ply)for glass up to 3 mm (1/8 in) and 175 micrometer film for glass over 6 mm (1/4 in).