The GeneralAire 6004 is the correct replacement valve seat for the following humidifier models:
The GeneralAire 975-1 Humidifier Valve Seat a replacement valve seat for the GeneralAire Legacy Drum Humidifier Model 65 and the 1040 Legacy Series Humidifiers. The 975-1 valve seat attaches onto the 81-21 float valve assembly and fits beneath the 975-6 valve shield to ensure the flow of clean moisture in your home. The GeneralAire model 1143 is an OEM replacmeent part.
GeneralAire 975-1 Humidifier Valve Seat specifications: