Couplings slip Within the finishes of two round ducts to become joined collectively then sheet metallic screws are mounted to carry it set up. Couplings might be essential at a certain sizing for example connections eighteen” and larger. The shaded spot in the image underneath would be the coupling. We https://round-conduit90122.pointblog.net/not-known-factual-statements-about-oval-conduit-82721072