Product review (1 stars): I wish I could give a negative rating...
I bought this pack in February and installed one of them right away. First difference I saw was the increased flow rate in comparison with a previous cartridge and a slightly mineral taste of the water . I thought the taste would go away after a couple of gallons, but it did not. Then I noticed that the filtered water was leaving white residue on a surface after drying out.
Now I have a suspicion that the manufacturers used some "unorthodox" materials when they built these filters, but to confirm that I would have to open one of them.
At least the filters were cheap... but I would never recommend them as replacement for a real thing.