Mylar Sheet is generically used to refer to polyester film or plastic sheet. However, it is also a registered trademark to brand a specific family of plastic sheet or mylar sheet 0r mylar paper products made from polyethylene terephthalate (PET). This durable polymer resin is made by stretching the synthetic fibers of PET. Polyester film/plastic sheet is manufactured in a range of different styles, finishes, and thicknesses. These mylar films are used in a variety of applications, across large scale industries.