Couplings slip Within the finishes of two round ducts to get joined together and afterwards sheet steel screws are fastened to hold it in place. Couplings might be essential at a particular dimensions for instance connections eighteen” and bigger. The shaded space during the graphic below may be the coupling. https://round-conduit13455.vblogetin.com/42438841/not-known-factual-statements-about-oval-conduit