Product review (4 stars): Almost as good as Vicks; way cheaper
I'm using these in three different Vicks warm mist humidifiers (and not for the Honeywell humidifiers these pads are officially for).  They are not as effective as the ones from Vicks, but they are boat-loads cheaper.  They are also much bigger than the ones from Vicks, so you use a lot less.  The down side is that you have to chop them up into pieces with scissors.
It's a trade-off I've been happy to make to save some money.