Product review (3 stars): Does it's job, but doesn't last long
This filter does what it is supposed to do, but there are a few issues I have with it.
1) It ships folded in thirds, which makes it hard to fit properly into the humidifier as it comes with creases in 2 places. It should ship circular
2) It does not last very long.  Perhaps this is just life with an evaporating humidifier, but this filter will go 2 to 3 weeks before it becomes moldy and needs to be replaced.  That said, I'm sure if I used distilled water that might be less of an issue, but it is what it is.  Plan to replace this regularly.