Product review (2 stars): Just not very durable...
First, you have to be very careful the humidifier is compeltely dry if you plan on not running it fora  while, lest these filters are compeltely ruined by mold. Secondly, after washing them, they just get a little bit crumbly and fall apart. They aren't super expensive, but its still a nuisance for a filter that is supposed to be reasonably long lasting.