Product review (5 stars): These are NOT used
I don't know why some folks have called these "used."  They are not used.  They come with a coating from the factory that is a rough, white, powdery-type coating.  This is intentional, and is not from hard water stains from this item being used.  It fits perfectly into my filter frame, and allows me to get another couple of seasons out of my great humidifier.  I really like this humidifier and would recommend it to anyone.  I've had it a long time now.  Once it kind of locked up on me when I started it for the first time one season, but it was because of excessive hard water buildup that had tried on the unit.  I removed the hose inside (remove the small retaining clip) and flushed it out and it worked fine then.  It's a great product that saves you money from not buying the traditional paper-based filters.