I am trying to identify a mystery wall receptacle that I have in my house (built in the 60s, USA). I have one in the living room next to a fireplace, another in a bedroom. It looks somewhat like the C8 socket, but is more rectangular and rough-looking.
Does anybody know what this is?
EDIT: added opened picture
Best Answer
Thanks for providing the "opened" picture, which clearly reveals that this is 300 ohm TV (and/or FM radio) antenna twinlead.
Not quite as obsolete as a buggywhip, but pretty close.