Flat Oval Spiral Duct Check out the below online video to see the set up of oval duct and fittings. Notice that the reducer getting used is undersized on its collar permitting the oval duct to slide more than the collar. They are utilizing Unistrut with threaded rods as hangers https://ovalconduit12334.bloggip.com/36757774/what-does-oval-conduit-mean