Product review (3 stars): Make sure you read dimensions - not 6" across!
I was in a hurry and didn't read beyond the 6" in the description, so make sure you read the dimensions.  I measured my vent cover outside and it's 6" between the screws, so I thought that was the size - it's not!  I went back and read the description, which states it's 9" with a 6" opening.  I measured the opening and got 7", but too large at any rate and needs to go back.