This HumidAire 3i to H4i Conversion Kit allows new H4i water chambers to be used with older HumidAire 3i heated humidifiers. WIth the Conversion Kit you get the convenience of added water capacity and the compatibility with the new Long Life H4i Chambers.
Each kit includes a new flip top cover, seal, cleaning plug and standard H4i water chamber. The kit fits very quickly and easily onto any HumidAire 3i (H3i) Heated Humidifier and is a one time purchase.
Resources: HumidAire 3i to H4i Upgrade Instructions (PDF)
Usage Information: Once you've upgraded your HumidAire 3i with the Conversion Kit you should purchase H4i chambers for all future chamber replacement needs.