Product review (3 stars): additional review
This filter material is a must to operate air o swiss humidifier.  When it works, I don't have to worry about mineral deposits in the water tank.  It must be soaked in water first, but I am finding that 1 out of 3 bags in the box may not work.  Water in the tank does not drip toward the main body.  I can't blame the granules 100%, but I think we may be being sold expired product that is dried out.  Despite some savings here, I plan to buy from the manufacturer's site.