This is a BRAND NEW Goodman/Janitrol/Amana 2 Stage Gas Furnace Air Pressure Switch. The Goodman/Janitrol # is B13702-02. One switch is rated at .35" w/c and the other is rated at .85" w/c. Switches also have part #s MPL-9300-V-0.85-DEACT-N/O-VS & MPL-9300-V-0.35-DEACT-N/O-VS Thanks for looking and good luck! Many older switches are metalic but they have all been updated/replaced with black plastic switches! They are direct replacements!
An air switch is safety designed to ensure that your inducer motor is running at the proper RPM, and creating the proper vacuum for your furnace to flue safely.