The air duct reducer or increaser is used for connecting solid or flexible ducts in ventilation systems, creating a stable connection between air ducts while maintaining airflow efficiency. Widely used in HVAC, ventilation, heating and cooling, fresh air supply systems, bathroom or kitchen exhaust, grow tents, dryer vent adaptation, cooker hoods, air-cooled hoods, embedded fans, roller dryers, dust collection systems, etc. Specification Material: Galvanized Steel Color: Silver Tone Size: 100mm Male to 80mm Male Round Duct Reducer Adapter (3.94 Inch to 3.15 Inch) Smallest Outer Diameter: 80mm/ 3.15 Inch Biggest Outer Diameter: 100mm/ 3.94 Inch Length: 120mm/ 4.72 Inch Thickness: 0.6mm/ 0.02 Inch Package List: 1 Pcs x Galvanized Steel Round Duct Reducer Advantage: One-piece design, made of good galvanized steel material, the round duct reducer is sturdy, does not easily rust, and highly fits other ventilation systems products. Raised edges on both openings provide a better grip for connecting pipes, and this duct reducer has a crimped design on the small end of the duct to fit inside the next section of ducting easily, making them firmly connect and work stably. Instruction: Simply insert the straight or flexible pipe, secure it with the steel clamp or tape. NOTE: Please check the outer diameter of the pipes before purchasing.