Product review (5 stars): LOVE THESE!
LOVE THESE!!! Do not settle on cheaper versions, these last forever and you get your money's worth out of them and THEN some. Made the mistake of buying an off brand on here to save a few pennies. NEVER AGAIN.

They don't get "skunky" or "slimy" for at least a month PLUS worth of use. We use ours with the Antimicrobial cleaning cartridges for extra protection. Extend the life of your machines! We use ours 24 hours a day, 7 days a week as a.) we have a SUPER dry house, b.) 3 out of 5 family members with asthma and allergies and c.) best white noise EVER.