Product review (5 stars): These work great!
I cannot believe how functional these filters are.  They capture a lot of the minerals that you would otherwise have to clean out of your humidifier.  So clean up, though still important, is hugely easier.  And taking a tip from another reviewer, I started soaking the filters in white vinegar (which I also use to clean the machine's heating well) overnight.  They come out like new again when you rinse them.  Not sure how long they last, but I am on my third or fourth use of the original ones.  Thanks for the great idea!