Higher Output Furnace Humidifier Water Pad. It fits Aprilaire 350, 360, 560, 560a, 568, 600, 700, 760, 760A, 768, #35 & 400A. It is a replacement pad for your furnace humidifier, using up to 50% less water. The anti-microbial treatment helps protect the filter from the growth and migration of mold, fungus, algae, and bacteria. For best performance, change the pad at least twice per heating season, or more frequently depending on water conditions and frequency of use.