Product review (5 stars): Works great
Weve used these for a couple of years now in a sonic style cool mist humidifier and they work great!  There us d to be a slimy film in the humidifier tank after less than a week of use.  With two of these in a 1.5 gal tank, we only clean it out once a month and there is still no slime.

I would caution anybody who had a demineralizer or carbon filter in their humidifier: these did not work at all for us until we removed both of those items from ours.  I would guess that they end up filtering out or neutralizing the silver particles.