Product review (5 stars): Better than the 3rd party substitutes
I tried an Ace Hardware alternative... too short. Went back to the original. The HM-3500 humidifier I put this in is one of the most reliable appliances I ever owned. I don't think they make it anymore but a few years ago when I needed a 2nd humidifier I found new old stock (a car term for parts that are new but no longer made).