Product review (4 stars): EXACT REPLACEMENT PROFESSIONALS USE
This is one of those products that are made for a specific piece of equipment that no one ever gets too excited about. It is the filter used in Aprilaire furnace humidifiers. It is the pad that soaks up the water and pushed out into your home through the duct work via the system fan.  Let me tell you why purchasing these from Amazon will actually save you money.

I had a service call when the seasons change for the HVAC company to change from A.C. To heat. As part of the service regimen, they replace these moisture pads in the furnace. They are exactly the same pads that Amazon sells but they charge TWICE what it costs for me to purchase them here. Not only that but you can easily change these pads yourself.

My advice is, if you hire someone to replace these, purchase them on Amazon and save a lot of hard earned money.