Product review (5 stars): and buying in bulk you can sometimes get them at a better price. <$9 each
We waited far too long replacing our original water filter, which was disintegrating as we removed it.  Certainly follow the directions in terms of replacement times!  But these work well, and buying in bulk you can sometimes get them at a better price.  <$9 each.  For the benefit of extra humidity during the cold seasons in the house, well worth this investment.