GENUINE OEM Replacement Humidistat Fits all models with 4039 adapter (
Aprilaire Replacement Humidistat 4655. Fits models: 400, 400A, 400M, 500, 500A, 500M, 600, 600A, 600M, 700, 700A, 700M. Does not require 4039 adapter plate. More »
Posted by on 21 June