Product review (5 stars): Good pad for Aprilaire humidifiers
This water pad fits and works great in my Aprilaire furnace humidifier.  I used one pad for a harsh Minnesota winter, and I think the pad is about spent.  Too much mineral buildup.  If you live in an area with a more moderate climate or if you have softer water (ours is quite hard), you might be able to get 2 years out of one pad.