We pioneered the manufacture and use of spiral duct and fittings for heating, ventilating, and air conditioning (HVAC) in the ... USA. Our extensive lines of duct system products are engineered for performance and economy and continue to set the standard for the industry. We are the country's leading manufacturer of commercial and industrial sheet metal ductwork supported by our nationwide Duct Express fulfillment service and network of sales engineering offices and manufacturing plants. read more