PATIKIL 5" HVAC Duct Manual Volume Damper, Metal Adjustment Airflow Ducting Backdraft Damper Control for Air Ventilation System

Solid and well built and still 5 stars even with the following design issue.Its a real beauty honestly.It does fit small as others have said, about 1/4”, so you have to “lightly” crimp the ducts connecting to it(pre-crimped ends won’t work as they will line up exactly with damper edge)And while you use crimped ends, the damper however fits INSIDE the crimped ends unlike a regular crimp connection. See photo

it solved the issue I had with the registers in one location taking all the forced air, i looked around in the home centers and couldn't find a solution since i have an old home, i had to do some minor modifcations to the existing Duct but other than that it was a breeze, this Damper can not be cut or drilled so it will need to be a tight fit

I needed to balance out the air flow within my home, half the house gets strong air, the other half, not so much. These worked amazing to minimize the air flow on the ducts that got more air so it can then flow through to the remainder of the house. Great quality, would recommend strongly if you have the same problem!

I purchased this for a duct project, and it worked great.

Finally found the perfect damper for my basement reno HVAC extension. It's seals the duct completely and cuts off heat from basement of I need to. This was the needle in the hay stack