Used Black Western Electric / Bell System Vintage 4 Prong Telephone Plug.
Connections are made by pushing in the spade terminals on your cord into the slots -see photo.
Note these are 50+ years old and fragile. Do not over tighten the screws or the Plastic will break!
No returns on plugs broken through the screw holes from over tightening.
Scuffs Scratches Oxidation and Wear.