Product review (5 stars): Easy to install and works.
We have hard water with a slight after taste.  This seems to take care of that.  My refrigerator has an idicator light that tells when to replace - unscrew the old one.  Line up the arrows and screw in the new one.  Quite frankly the hardest part is purging the gallon or so of water that the instructions call for.  At home it lasts about 6 months and I do not notice any significant pressure loss while it ages.