This Master Flow flexible duct is the perfect addition to your heating and cooling system. With a diameter of 14 inches and a length of 25 feet, it is made of durable fiberglass material that is corrosion and rust resistant. The duct is also insulated to ensure maximum efficiency and comfort in your home or office. The Master Flow F8IFD14X300 model is round in shape and features a silver jacket for easy identification. It is a great choice for anyone looking for a reliable and high-quality flexible duct. Plus, with free shipping included, it's an easy and affordable upgrade for your existing system.