4 inch x 8 foot Flexible Aluminum Semi-Rigid HVAC Duct (Double-Lock)

The Lambro 4-inch x 8-foot flexible aluminum semi-rigid (double-lock) duct is more durable than traditional versions. It is ideal for general HVAC venting applications that require air expulsion from the home. Suitable for HVAC systems, our semi-rigid ducts ensure minimal air leakage and optimal performance, resulting in significant energy savings and improved indoor air quality.

The duct is ideal for new and replacement installations. It is flexible, and the corrugations throughout prevent collapsing and allow easy duct bending when needed. Aluminum is corrosion-resistant, non-combustible, and flame-resistant, with a maximum operating temperature of 430°F. When installing the duct, you can cut it to length to allow for stretching for maximum airflow.

A semi-rigid and lightweight non-insulated flexible duct, the double-lock manufacturing process uses a dead soft aluminum strip spirally wound and mechanically joined together, forming an airtight and leakproof double-lock seam. This self-supporting and corrosive-resistant product provides excellent strength and flexibility and is adaptable to any low—to high-pressure heating, ventilation, and air conditioning system.

The minimum bend radius to the center line is one diameter. However, our recommended radius is 1 ½ diameters under accepted practice. The aluminum ducting can be easily cut to size and formed by hand.

Please be sure to check local building codes before installation.