Product review (5 stars): Replacement filter for Duracraft Humidifier
These filters are simple and inexpensive. One lasts a whole winter season, although you may need to replace it once.  I use the humidifier in the winter months when the heat dries out the house. It keeps me healthy and comfortable. I have tried almost every portable humidifier out there. Many promise no maintenance and no filter replacement, etc. I keep going back to my Duracraft Evaporative Humidifier which I have had for years. The other humidifiers do not last or the "permanent filters" fall apart and are costly to replace. The Duracraft does require regular simple maintenance. I rinse out the tank and filter every time I fill it, rotate the position of the filter, and periodically clean the tank with white vinegar.