Product review (1 stars): IT SUCKS!
Bought a bunch of these replacement filters (10, I believe) for my Honeywell 2000 series humidifier.
This "enviracaire" blue wrapping was a new thing for me.&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/HONEYWELL-ENVIRACAIRE-HAC-504-Replacement-Filter-Pad/dp/B00007E7RZ/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">HONEYWELL/ENVIRACAIRE HAC-504 Replacement Filter Pad</a>&nbsp;Never seen it before, but figured what the heck, maybe it's new technology & will improve the filter's capability.

WRONG!!

My experience has been just the opposite.  1) It doesn't last as long, working only 2-4 weeks before it's efficacy diminishes, whereas the 'older' filters with the plastic/wire mesh would easily last 3-4 months, sometimes longer depending on use.  2) Using the old filters, I would often take them out after some heavy use, clean them, and descale them before continuing to use them.  Only after months of use & hard build-up would they lose their efffectiveness & need to be changed.  With these "enviracaire" filters the build up isn't heavy at all, it maybe something else (see #5 below), they just lose their effectiveness very quickly.

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3) I've been using humidifiers for nearly 9 years.  I have a wine cellar & walk-in humidor, and for those of you who partake in those hobbies, you know how important it is to maintain proper storage conditions.  So you might say that, yes, I do have experience in the use of humidifiers and environmental control.  4) I bought my last batch of (these) replacement filters from KAZ.  When I began using the filters & encountering problems I contacted kaz to complain.  Well, the customer service person who contacted me proceeded to tell me how it must be MY HUMIDIFIER that's not working properly as the filters work fine in hers!  RIGHT!!!!!  Does she use hers as extensively as I use mine?!  I've been using the current humidifier(s) for three years with no prior problems to this!!!

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5) Now here's the worse part, IMO.  WHAT'S WITH THE FILMY/MOLDY STUFF THAT BUILDS UP?!  When I began using these "enviracaire" filters, I began seeing a filmy, moldy build up in my humidifier's water system.  Even after I thoroughly clean the filter housing & install a new filter, at about the 2-4 week mark (when the filter's efficacy starts to diminidsh), the unit gets this filmy/moldy build-up in the filter housing compartment and in the water (but it doesn't get into the tank).  Whether I use a few drops of a bacteriostatic or descaling in the water tank or not doesn't make a difference.  Never seen that before, never seen it with the older filter types!!  This filmy stuff may be the reason for the decreased function of the filetr, at least that's what I suspect.

So!  Should you buy this filer?

You decide.  Personally, I think that the manufacturer needs to know about these problems and take care of them.
As for me, I'm trying desperately to find the older style filters that had a wire-like/plastic outer mesh.&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Honeywell-HAC504-Replacement-Humidifier-Filter/dp/B0000WM2IG/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Honeywell HAC504 Replacement Humidifier Filter</a>&nbsp;They seemed to work just fine!!