This Bryant single 2-prong electrical center-hole mounting receptacle
attaches to the faceplate with a steel lock nut and also has a fiber
hex nut over the steel nut. 

The one in the photos came off a Kimball-Welte roll changer.

Thanks,

Dave Krall
Hammond, Indiana
djkrall@sbcglobal.net.geentroep [delete ".geentroep" to reply]

[ https://www.mmdigest.com/Attachments/25/07/16/250716_101107_100_5556.JPG 
[ https://www.mmdigest.com/Attachments/25/07/16/250716_101107_100_5557.JPG