Product review (5 stars): Preliminary results: Excellent!
I've had a Kaz humidifier for years now, and have suffered with buying those awful paper filters that die after a few months, Plus, they cut the thickness of the filter, which means you don't get as much water vapor into the air.

This filter is made of Dura-ester, not paper, and is almost twice as thick as the last replacement I bought. Relative humidity in the space I'm trying to boost is 50% and the outside temp is 11F!

Unless this filter dies prematurely, I expect it to last for the rest of this winter and several more winters to come. As a tip, try adding a bit of CLR to the water when you clean the humidifier to keep mold, etc., from growing and making for easy cleaning. You only have to add it after you've cleaned it. It stays effective as you keep adding water between cleanings. Hope this helps.