This ducting is designed for various ventilation, circulation, and heating/cooling transfer applications. The internal layer is made of heavy-duty dual aluminum foil that is fire/flame resistant. Its outer layer utilizes dual PVC thermoplastic that protects the aluminum from cuts and tears while stopping leakage. Each tube is held together by an internal steel-wire spiral that's flexible and easy to install in hard-to-reach places. Includes two stainless steel clamps for easy clamping and installation. Set includes two steel duct clamps that secure the aluminum tubing to your inline fan. Fastens the loop using a Phillips screw. Fastening is done by removing the clamp from the end of the cable. This set can be shortened for retrofit projects like closets, racks, and cabinets.