Product review (2 stars): Doesn't last long.
The Honeywell HAC504 is a typical wick "filter" that gets full of mold and dirt in a matter of weeks. This replaces the Honeywell HAC529EX which had a UV treatment that killed mold, never got dirty and was $5 cheaper. I'm still on my original HAC529EX from 1997 and it's still humidifying our basement dungeon.