Product review (4 stars): Good preventive maintenance
This was just the right replacement for my humidifier filter, which was never going to need replacement according to the product literature.  :-)

When the mineral buildup got too heavy on my original filter, I tried soaking it in a tub of vinegar and scrubbing it with a toothbrush.  Only some of the crusty stuff came off.  What's more, with all of the scrubbing I accidentally tore a few pieces of the metal weave, which left sharp edges poking out.

So I looked on-line to see if I could buy a replacement - and here it was.  I was a little surprised that it didn't come in a plastic frame, but it was pretty easy to snap the frame off the old one.

Thank goodness there are still some appliances that you can maintain with new parts instead of having to take the whole thing to the dump when trouble strikes.