In order to do a takeoff, you will have to have the ability to comprehend what rectangular duct and fittings appear like And the way they are represented about the drawings. The fitting is comprised of one piece although the opposite connection system requires two parts, the saddle-faucet and reducer. https://ovalconduit13344.blogocial.com/5-tips-about-oval-conduit-you-can-use-today-72437606