4" x 25 Ft. Flexible Semi-Rigid Aluminum Duct

This 4 inch diameter by 25 foot long flexible semi-rigid aluminum duct delivers reliable, code-compliant venting for clothes dryers and other exhaust applications where traditional flexible ducts fall short. The semi-rigid aluminum construction means it will not collapse, sag, or kink during installation or operation, giving you a safer, longer-lasting vent run than vinyl or foil alternatives. Built flame resistant and durable, this duct is designed for professionals and homeowners who need a flexible solution that holds its shape and maintains airflow efficiency over the full 25 foot length. Lambro Industries engineers this duct to meet the demands of gas and electric dryer installations, bathroom exhaust systems, and similar venting needs where building codes require metal ducting.

• Semi-Rigid Aluminum Construction: The aluminum forms a flexible yet self-supporting structure that holds its shape without external framing. You get the routing flexibility of a flex duct combined with the rigidity and safety of metal, reducing installation time and eliminating the sagging and crushing issues common with vinyl products.
• Will Not Collapse, Sag, or Kink: The engineered corrugated design maintains an open airway even when bent or routed through tight spaces. Your dryer or exhaust fan operates at full efficiency because the duct holds its internal diameter, preventing airflow restriction and lint buildup that lead to fire hazards and appliance damage.
• Flame Resistant: Aluminum is inherently non-combustible and meets fire safety standards for dryer venting. This gives you code compliance and peace of mind, especially critical in dryer exhaust applications where lint accumulation and high temperatures create fire risk.
• Durable Material: Aluminum resists tearing, moisture, and temperature extremes far better than plastic or foil ducts. You install it once and it stays intact through years of use, eliminating the need for frequent replacement and reducing long-term maintenance costs.
• 4 Inch Diameter: The 4 inch size is the industry standard for residential dryer venting and many bathroom exhaust fans. This ensures compatibility with standard dryer outlets, wall caps, elbows, and clamps you already have or can source locally.
• 25 Foot Length: The continuous 25 foot run lets you connect appliances to exterior vents without splicing multiple short sections together. Fewer joints mean fewer potential leak points, better airflow, and faster installation on longer runs between laundry rooms and exterior walls.

This duct is compatible with 4 inch dryer outlets on gas and electric clothes dryers, 4 inch bathroom exhaust fans, and other 4 inch diameter venting applications. You will need 4 inch hose clamps or foil tape to secure connections at each end. The duct ships in a compressed coil and requires two people to fully extend it to the 25 foot length, as one reviewer noted it takes effort to stretch it out completely.

Route the duct with as few bends as possible to maintain maximum airflow. Secure each end with metal hose clamps and seal joints with metal foil HVAC tape, not plastic duct tape. The semi-rigid structure allows you to shape gentle bends and curves without needing rigid elbows, simplifying routing through walls, floors, and crawl spaces. Clean the interior periodically by disconnecting it from the appliance and using a vent brush or vacuum to remove lint and debris buildup.

• One 4 inch diameter by 25 foot length flexible semi-rigid aluminum duct

A: Yes. The duct is constructed from flame-resistant aluminum, making it suitable for both gas and electric dryer venting. The material is non-combustible and meets fire safety standards required for dryer exhaust systems, which is critical given the high temperatures and lint accumulation in dryer vents.

A: The duct ships compressed and requires stretching to reach the full 25 foot length. Multiple buyers confirm it measures 25 feet when fully extended, though one reviewer reported only achieving 15 feet without applying significant stretching force with two people. Plan to use two people during installation to pull the duct to its full length before securing the ends.