Product review (5 stars): The built-in exterior support screen that comes with this is an essential
I like the humidifier that I use these in but the brand matching-named filters didn't have the exterior metal support screen.  They tended to gradually slump under their own weight after wet and more so after I tried to clean them with vinegar (weak acid to dissolve mineral deposits).  When they'd slump the fan would draw a lot of air over the resultant 1" or so gap between the top of the filter and the bottom of the fan housing rather than through the filters.  These reach all the way up and stay that way because of the support screen.  They're also much less expensive and shipped quickly without excessive packaging.