Skuttle A04-1725-045 Replacement Pad, Filter, with Wick, for Model 34,55 Humidifier Fits Skuttle models 34 and 55-UD humidifiers. Skuttle furnace humidifier filters (evaporator pads). Evaporator pad includes wick. Honeycomb filtration to trap mineral pollutants found in water and help prevent them from entering your home. For optimum performance, replace pad once every 6 months or more often in hard water areas.