Product review (5 stars): I paid almost as much for one mold & mildew-resistant ...
I paid almost as much for one mold & mildew-resistant filter as I paid for these.  Within three weeks, turning the filter every few days, the mold-resistant filter was developing ominous black spots, so I ordered these, figuring it would be cheaper to replace the filter every three weeks or so.  It has been over six weeks and there is no noticeable deterioration of the first filter.  I am thrilled.