Product review (3 stars): Broan, you can do better.
The problem with these is the sizing.  As they are Broan/manufacturer correct filters, and I highly doubt there are other alternatives, you are stuck with the design and sizing.  These could be 1/4" larger in length and width.  I had to try and stretch them to cover the vent opening, but my efforts weren't fully successful.  Then, because the attachment tabs are limited in number the filter almost wants to fly away and get sucked into the fan.  What can you do....