Product review (5 stars): Great product
I would not skip and buy off brand filters.  These are the good ones, that filter out most contaminants.  Fast shipping, great packaging.  It is worth buying more than one, as you can save if you bundle, and you know you will need more.  The replacement is very easy, and there are instructions provided.  I immediately saw a difference in water pressure upon replacing.  I usually do this once a year, but will now do it twice a year as per the manufacturer.