Galvanized construction. Allows you to vent multiple areas with one fan. A Duct Wye branch is the fitting to use when you need to branch off your duct run to a smaller size. The sizes are listed for the inlet side, the discharge side and then the branch side. All wyes are manufactured from the highest quality galvanized steel. They are perfect fittings for maintaining maximum airflow through your system while branching off to multiple locations.