Product review (5 stars): Great because they clean the air as well as humidify
I buy a set of these filters for our three large humidifiers every winter.  It makes an incredible difference in the output of water when you have a fresh filter annually.  What I like about these (as opposed to their predecessors or "clone" knock-offs) is that they have an air filter as well as a water wick, so they purify the air while they humidify -- a great saving on electricity if you need otherwise to run a separate air cleaner.