Cheaper and makes less landfill than buying entire new cartridge
I LOVE that I can refill the plastic cartridge that came with my humidifier - instead of putting the old cartridge in landfill and buying a new one.  So much less wasteful!  Also cheaper to buy just the refills.  I saw another comment saying they have to use 2 refills to fill the cartridge, but this is my 3rd year using the refills in 3 separate humidifiers and I only use one refill packet per cartridge when I refill (all 9 times) - and it lasts entire 3 winter months.
Rating: 5 stars