The Air Systems International 12" Diameter Air Duct is a galvanized steel circular duct ideal for HVAC and exhaust ventilation applications. It features a 26 gauge thickness with a smooth interior for efficient airflow. The ducts have interlocking connections for easy assembly and can be cut to desired lengths. Diameters range from 4" to 16". These air ducts meet SMACNA standards and offer corrosion resistance. With various diameters and connection options, these galvanized steel ducts are versatile for commercial and residential HVAC installations.