Speedi-Products SM-3060GO 06 6-Inch Oval by 60-Inch Length 30-Gauge Galvanized Oval Pipe 6-Inch Oval Sheet Metal 30 Gauge wall stack duct For interior wall supply and return air ducts Seal joints with approved duct mastic sealants Insulate Ductwork for improved energy efficiency and comfort Consult your local building codes for approved installation practices