Product review (5 stars): Better than expected
These replacement filters are better than the original ones sold by Sears.  After reading some reviews that stated they didn't work as well as the original filters I was reluctant to try them, but I'm glad I did.  These filters are much more durable than the folded paper ones.  And as far as putting humidity into the air I don't see that there is any difference; I am filling up my water bottles at the same rate as before.  I live in the north, so on warmer days during the winter months my furnace doesn't kick on as frequently and the radiators don't dry out the air as quickly.  Therefore it is easier for the humidifier to maintain the relative humidity in the house.  On very cold days (especially when it is below 0 Degrees F), the furnace kicks on quite a bit, the air is drier and the humidifier has a harder time keeping up.  That's going to be true no matter which type of filter you happen to be using.

Although it is recommended to change the filters each month, I usually leave these filters in for two months before changing them, sometimes longer.  I add a small amount of BestAir Humidifier Bacteriostatic Algae & Odor Water Treatment (comes in a green bottle) to each container of water and I have not had any problems over the last 3 years.  I use these filters both at home and at my place of business and I recommend them.  In fact, I am awaiting shipment of two sets of them to replace the filters as I write this.  Hope this helps.