Mylar is a trade name owned by DuPont and is a polyester film used for its high tensile strength, chemical and dimensional stability, transparency, and electrical insulation. Mylar can be aluminized by spraying a fine film of metal onto it. The result is a product with reduced permeability to gasses and reflects up to 99% of light. Mylar is similar to aluminum foil because it has a shiny reflective side and a dull side. Unlike foil, Mylar does not tear easily.