Polyester films have excellent dimensional stability, high tensile, tear, and impact strengths, and ultimate elongation up to 120% of its original dimensions. These films exhibit low water absorption and good resistance to oils, greases, strong acids, and organic solvents. They also retain electrical properties, dielectric strength and dielectric constant in continuous operating temperatures from -100°F to 350°F (-73°C to 177°C). Applications include transformer and capacitor wrapping, printed circuit board fabrication, splicing tapes, composite bonding protection, and low-cost masking.