Product review (4 stars): Works fine
Works fine ... just don't be alarmed when the filter seems to be flat when it's removed from the box. It does NOT come out perfectly round like the photo shows. However, once it's installed in the humidifier and takes in water from the tank, it will form a round shape like it should.

We have hard water in our area (and don't use a water softener), so they probably don't last as long as they would in a soft-water environment.