Material: GALVANIZED STEEL Assembled Product Length: 24" Assembled Product Height: 3.25" Assembled Product Width: 10" Diameter: 3.25" . Used between wall studs for venting, heating and air conditioning supply and return duct Stack duct is supplied in halves for assembly Two halves or two "L" shaped pieces are required to make a complete rectangular 4' duct Galvanized steel construction 3-1/4" x 10" x 24"