Up for sale is a used Air Pressure Switch
for various Freightliner semi truck models.
It may fit other makes as well.

There is no part number on the switch.
This switch has normally open (N.O.) contacts; it triggers (contacts close) at 8 psi.
It has a male 1/8"-27 MNPT (Male) air line connection. Switch has been tested working.

Please see photos.
Questions welcome. Thanks for looking.