Speedi-Products SM-3036GR 06 6-Inch Diameter by 36-Inch Length 30-Gauge Galvanized Sheet Metal Pipe 6-Inch Sheet Metal 30 gauge round pipe Used in HVAC warm air supply, return and exhaust duct systems Seal joints with approved duct mastic sealants Insulate Ductwork for improved energy efficiency and comfort Consult your local building codes for approved installation practices