Metallized films (or metallised films) are polymer films coated with a thin layer of metal, usually aluminium. They offer the glossy metallic appearance of an aluminium foil at a reduced weight and cost. Metalized films are widely used for decorative purposes and food packaging, and also for specialty applications including insulation and electronics.

PET is a hard, stiff, strong dimensionally stable material that absorbs very little water. It has good gas barrier properties and good chemical resistance except to alkalis (which hydrolyse it). Its crystallinity varies from amorphous to fairly high crystalline; it can be highly transparent and colorless but thicker sections are usually opaque and off-white.