Product review (4 stars): I bought a 3-pack of these for a humidifier that ...
I bought a 3-pack of these for a humidifier that specified AC-818 replacement filters. These were a little (appx 1") longer than the humidifier's filter support cage so I trimmed the replacement to fit with ordinary scissors. The replacement seems to be doing OK and now I won't need to hunt for replacements for a couple of years.