Product review (5 stars): Good clean, clear water.  I have very hard water, and these work great so far.
I bought these last week to replace an OEM filter I had been using.  They purged quickly at about four gallons.  Water is very clean, not airy, crystal clear, and taste is fantastic.  If they hold up, I will certainly buy more from this manufacturer. The price is very competitive as I bought a bundle at once so I don't have to remember every time.
 I use at least two-three glasses a day from my fridge.  The OEM ones last me typically about a year before performance dwindles and taste is compromised.  Manufacturer recommends every six months however to maintain taste, however I hardly notice after many months past that.  My refrigerator's filter reminder is also on a year timer.  So that makes it a bit easier to remember for me.  I will report later if I notice a strong difference in time/taste performance.