Product review (4 stars): Good product to use
The HAC504 Humidifier Filter works well as it catches most dust and mites from the air and replaces it with humidified air.  Very important in my home because the air is heated and very dry.  Adding moisture is imperative during the winter months and this filter does the trick.  I ordered 2 because I am sure I will use the humidifier for the next two years prior to replacement.  Product came within 3 days of order.