Product review (5 stars): Metal-free filters do a great job without the problem of bad odor that comes from the metal ones
These filters were purchased for the Vicks/Kaz Germ Free 3900 and the Honeywell germ free 350 humidifiers.  These filters work in both units, perfectly.  We've tried many filters and these are by far, the best.  There is no metal in these filters, so you don't have to deal with the horrid odor those types of filters put out.  These are the correct thickness, and pass the water through sufficiently so that you get the moisture you need right away.  Some filters we bought in the past that said they were for these machines, were so thin they collapsed or fell part way over inside the machine and passed the water through very slowly.  That doesn't happen with this compatible filter.  It's quality all the way.  The photo shows that it comes in a box.  Ours arrived in a sealed green plastic bag with the label on the bag, which contained each filter in its own sealed plastic bag.  They were shipped by Amazon and arrived in perfect condition.  It's nice to finally find the best filters that don't stink up the room, and truly get the job of humidifiying done the way you would expect.