Summary: I was extremely disappointed in the back draft damper. The flapper just hangs in the duct, it does not have a flange to close onto. You can see lots of daylight looking through the duct to the fan. If you buy this fan I recommend you buy an in-duct damper for it and remove Panasonics cheap flapper.
Summary: This fan is so quiet I have to go check to see if I left it on. It can't be heard in the room above and is almost impossible to hear through a closed door. Compared to this one the old one sounded like a dryer full of rocks.