Mylar A is a transparent, flexible polyester (PET) film available in thicknesses from 19 to 350 µm (48 to 1400 gauge), offering superior dielectric strength up to 21 kV, tensile strength of 175-275 N/mm² longitudinally and transversally, and elongation at break up to 230%. It withstands temperatures from -70°C to +200°C (melting point 254°C), with low shrinkage (1.1-1.5% at 150°C/30 min) and density of 1.39 g/cm³. Key features include excellent moisture and chemical resistance, high insulation resistance (10^13-10^18 ohm·cm), balanced mechanical properties, and non-brittle durability without plasticizers, ideal for electronics insulation, barriers, and industrial applications.