I have been using these for several years now.  I was hesitate at first because they cost more than the rest.  After using them I understand why they cost a little more, they work so much better.  I drink as much as 2 gallons of water a day and want it to taste as fresh and clean as possible.  I wish the filters lasted longer because I go through at least 2 a month, but I know it all has to do with the quality of the water going in and not the quality of the filter.  They do have a tendency to get an air pocket in them that slows down the filtering, and it can be a bit of a pain to get out at times.  I tried all of the others before coming over to Zero Water and I wish I had tried them sooner.  They are the best.