Product review (5 stars): Simple and Effective!
Quick and easy replacement.  This 2 pack of replacement filters is great - one filter pretty much lasts us for winter as we only run the heat about 3 months anyway.  Filling the register every night before we go to bed is enough to humidify the bedroom.  Much better and safer than our old humidifier - that gave us upper respiratory infections even after extremely thorough cleanings.