Product review (5 stars): I use it in my Honeywell HCM-350
Reasonabley priced. One cap full for each gallon of refilled water. 32 oz can last a year, depending on useage and how steday your had is when you fill the cap. Emits no order, yet keeps my 4 month old Honeywell free of the "slime" that messes up almost all humidfiers. Because of this HCM-350, no water ever enters any working part other than as a vapor. Byt this and two extra filters at the same time you buy this Honeywell and save on triple shipping.
Plan ahead.  Wish this product had been available 50 years ago.