Product review (2 stars): Smaller than normal WF2 filter, no structural integrity
The filters do NOT contain aluminum ribbing. They have much less structural integrity than I would come to expect from a WF2 filter. They are also shorter than the normal WF2 filter. I have a Vicks CoolMoisture humidifier. Normally the filter would fill the tray completely with a snug fit. These filters have almost an inch to spare on one side. And with the lack of ribbing, they will slide around in the tray when moved.
I'm not impressed with these filters and will not be buying again.