Product review (4 stars): Serves its function
It served its function.  Actually, have reordered it and on our 2nd set of these.  Last winter of 2009, we had used a a set of w as well from December to about April.  Only advice for others who like to buy one, don't forget to get those bacteriostatic water additive and/or humidifier container cleaning solutions to prolong the life of these filters and to minimize mold and/or algae in the water -therefore, cleaner and moistened/humidified cool blowing in to the room.