The sectional garage door ISO 20 is filled up with a 20 mm core of hard plastic foam which provides high thermal and noise insulation. All sections of the door are made of hot galvanized fine sheet iron and are lacquered with atmospheric impact-resistant primer coating based on polyester. Corner cross-beams, lead rails, as well as all door ferrels are also galvanized to avoid rusting so that you can enjoy your door for many years to come.