Product review (5 stars): Cheaper than Home Depot
Normally I would have drove up to HD to buy a replacement, but when I saw the price was at least [...] bucks cheaper here on Amazon, well there wasn't much question.  This is exactly the right filter for my Aprilaire 600 home humidifier system.  It was a quick and painless swap out and I learned a little about the cleaning of the holder when I did it.