Product review (5 stars): Really, the best.  Don't go generic, be careful.  USA Tested and approved.  Too expensive!
I've tried the generic ones, although expensive these last the longest with the least amount of aftertaste/taste to the water.  Safe bet, not cutting corners, USA tested.

Likes:
Excellent water taste
Excellent water clarity
Lasts the full recommended 6 months with normal use, not much if any reduction in water pressure
Perfect fit and installation
Top notch water filtration, you really can't do any better

Dislikes
COST!!!