Product review (5 stars): Works great for what it does.
I used this to transition from 3-1/4" X 10" rectangular vent duct to 7" duct when installing my range hood. I had 5 feet of 3-1/4" X 10" rectangular duct, which runs from the range hood up through the kitchen cabinet above and into the ceiling. Using that style of duct in the cabinet saves some space compared to round duct. In the attic I used this well made, heavy gauge transition piece to go to 7" round that exits into the vent cap on the roof. I pre-drilled small holes and then used stainless steel sheet metal screws to attach everything together and sealed it all with aluminum duct tape. It's rock solid and should not give me any issues in the future. With a high flow range hood and this size of duct, cooking smells are no longer a problem at my house other than the neighbors inviting themselves over for dinner!