Product review (5 stars): Works great!
These were definitely the official filters.  I used the pictures in other comments here to compare these to what I purchased at Home Depot a year ago, and discovered that one was a knock-off.  It had the fine print "this is not NSF certified" whereas these ones from Amazon do not have that line.  The one from Home Depot also had only one rubber washer around the neck, where these had two.