Flexible Air Ducts
Flexible air ducts are exactly what they say they are: flexible. This type of duct is also lightweight and constructed with a spring steel and spiral helix. This option is extremely useful in tricky and unusual spaces but, unlike rigid air duct options, it must be firmly supported and secured to prevent sagging, kinks, or bends.
Sheet Metal Air Ducts
Sheet metal air ducts are made of aluminum or galvanized steel. This type of air duct is the most durable. Galvanized steel duct would eliminate rodents from getting inside the ductwork.