PATIKIL4" HVAC Duct Manual Volume Damper, PP Adjustment Flame Retardant Airflow Backdraft Damper Control for HVAC Air Balancing System, Beige

This is a solidly-constructed damper. I didn't feel bad about spending $25 USD on it after receiving it. I did add a little weather stripping to each half inside up against the little ridge that stops the door from turning closed further, just to seal it a bit more, but it looks to be a 90%+ seal without doing that, at the least. Depends on your use case whether or not you will want to beef it up further.

Product works as advertised. I bought the 3 in version which does not fit a 3 in PVC pipe because its the outside dimension on the valve that's 3 in in diameter. Made it fit but what a pain.

It fits as discribe was able to switch from one to another with a turn of the valve

works like it should

This damper was supposed to be 75mm/2.95" ID, using calibrated digital calipers it was 1.3mm oversize in the ID, making it useless for a cemented connection to a 2.95" OD pipe. The overall length was wrong as well, it was 5.09". It is also not round, with the ID being 76.3mm and rotated 90 degrees it was 76.1mm. If you use duct tape maybe it will connect, but it will not connect using standard PVC glue because the gap is too big. Plumbing systems should not require tape, glue is the only way to make a reliable permanent airtight connection.The only reason this didn't get a 1 star review is because the actual damper valve closes snug and can be locked in any position between closed and fully open. Too bad the diameters are so far off or this would be a great valve.