Aprilaire4839 Maintenance Kit with Model 35 Humidifier Filter for Aprilaire Whole Home Humidifier Model: 600, 600A, 600M

The moisture content in the air in my home went to 50 in no time. This has been very important when one suffers from dry mouth, etc. I am very impressed with the results of this installation.

I did not give it a 5-star rating because it turned out to be a set for post 2007 500M humidifier and infeed tube was too short for my 2001 unit. Was able to adapt my old tube and use the set successfully

installed it and works fine...i would buy it again

Unit works great.

Worked fine. Expensive for a filter and a couple pieces of plastic