Powder coated corrosion resistant galvanized construction Duct Reducers are the perfect fittings to use when you need to change from one size duct to another size. All Reducers are manufactured from the highest quality galvanized steel. They are the perfect fitting to maintaining maximum airflow through your system while changing to the needed duct size. They can be used with fans, ducting, air-cooled hoods, and ventilation systems. This high quality ducting is the best on the market!