Product review (3 stars): Still wish they lasted longer!
This contains my previous reviews of the same product that used to be a three pack sold through Amazon(now sold as single Protec WF2 Extended Life Replacement Humidifier Filter through outside retailer). This purchase was a bulk 6 x single filter through AmericanWholesale.  Shipping through them was only $1.99, extremely quick and made me up my review 1 star. I also use the ProTec Humidifier Tank Cleaning Cartridges. A 2 pack will just last me the winter months. They do help keep the water cleaner and the filters lasting about 6 weeks each.
Old reviews: I purchase these every year for my Vicks humidifier. I have spent way beyond what the machine itself cost me on filters. Each filter lasts about a month to 6 weeks before getting moldy and stops wicking the water. I only use the humidifier for about 4 months in the Winter, which a 3 pack of filters is good for. I would use it all year if I did not have to keep replacing the filters. If someone knows a better choice of longer lasting filters, please post.(5/5/2008)
12/9/08-Too bad this is the only place I have easily found these. I cannot believe they have gone up $10 in cost since I purchased them a year ago (11/30/07)!