Product review (5 stars): Works as expected.
Buy these every year for our humidifier.  They last a few weeks with constant use of the humidifier.  Did find that if you turn your humidifier on and off every day or allow it to run out of water, the top edge gets hard and crusted quickly and the filter won't last as long.  We have hard water and a water softener in place, so that may contribute to the filter turning hard when dry.  When you do change the filter, allow it to dry until no longer dripping wet and it can easily be broken up into smaller pieces to fit in the trash.