Product review (3 stars): Okay filter, but too expensive
Used as a replacement filter for a Honeywell room humidifier.  Quality not as good as original filter.  These filters last for maybe a month if your water isn't too hard.  They are too expensive for having to be replaced so often.  By the time you buy enough replacement filters and Protec cartridges to last the whole winter, you could almost buy a new humidifier!