Product review (2 stars): Should have perforations on both sides
The instructions on the package say "Step 1: Push finger into serrated edge on each side and pull windows out. Discard"

Unfortunately only 1 side has a "window" to pull out!  My original matched the instructions but these do not.

I had the same problem with my last order from a different e-tailer.

I was hoping the problem was resolved by now or was dealer specific... but apparently not.

My workaround is to reuse the old box that had openings on each side and to swap out the thin carbon filter inside it.

It works, but is a pain.  Definitely not sure these things are worth the cost or trouble to replace....