Data storage devices—compact disks, floppy disks, and magnetic tapes—come in all shapes and sizes. The first magnetic tapes were made of thin strips of metal. In the early 1950s the DuPont corporation patented a thin, polyester film that revolutionized the magnetic tape market. Called Mylar, this plastic material is chemically stable and is virtually as strong as metal, yet heat-resistant and lightweight. Mylar has a myriad of uses and is used in the manufacturing of numerous plastic products, including photo negative sleeves, food wraps, and magnetic tape.