Genuine OEM Aprilaire humidifier evaporator pads (also called humidifier filters) manufactured by Research Products Corporation. Money-saving two-packs save on shipping and will last 1 to 2 heating seasons.

Humidifier pads / filters are one of the important parts of the humidifier. The humidifier pad is what the water flows across that enables evaporation of the water into the home. Replacing the pads once per year ensures that the humidifier evaporates the optimum amount of water to keep your home comfortable. You may consider replacing the humidifier pad more than once per year if you have hard water.

Replacing the humidifier pad / filter
Aprilaire pads / filters are designed to be easily replaced in Aprilaire furnace humidifiers. Simply by removing the humidifier cover, the pad / filter can be taken out and a new one slid into place. This can be performed by the homeowner in a matter of minutes.

Replacement humidifier pad fits model 400. (2-pack)