This is high quality duct work. Really like the heavy duty nature of the construction, and it looks great in black. I see in the reviews that there are issues with it being tight, but I found that while snug, it definitely fits 4 inch round ducts. A couple pointers - screw it onto the duct in a rotating motion; use pliers on the duct to bend the metal inward slightly so you have a decreased diameter to work with as many round ducts are not perfectly round and will have a section that needs to be bent to fit.Great quality / recommended.
Rating: [5 of 5 Stars!]