Polyester Films, also known as Metalized Polyester Film, PET Polyester Film, APET Polyethylene Teraphthalate Film, PETG Polyester Teraphthalate Glycol Film are flexible and dimensional stable, making it hard to tear. Typically resistant to high-temperature and UV, it is often used for electrical insulation, surface protection and packaging. Available with or without adhesive and in a variety of finishes, from clear to silver and many other colors or tints. Screen protector is an additional sheet of material commonly polyurethane or glass that can be attached to the screen of an electronic device and protect it against physical damage. Screen protectors are made of either plastics, such as polyethylene terephthalate (PET) or thermoplastic polyurethane (TPU), or of tempered glass similar to the original tablet or smartphone screens they are meant to protect. Plastic screen protectors cost less than glass and are thinner, around 0.1 mm (0.004 in) thick, compared to 0.3 to 0.5 mm (0.012 to 0.020 in) for glass. At the same price, glass will resist scratches better than plastic, and feel more like the device’s screen, though higher priced plastic protectors may be better than the cheapest tempered glass models.