Skuttle A04-1725-050 Replacemnt Pad, Filter for 85, 86 Fits Skuttle under duct humidifier models 85, 86, and 86-UD. Skuttle furnace humidifier filters (evaporator pads). Measures approximately 9 x 26 x 7/8. High performance, high output! For optimum performance, replace filter twice a season.