Found this little accessory while tidying up and though hmmm lets look inside...
.
And what do we see, well not much as to be expected.
The plug part is a ITT Cannon (AN3106 !) connector used on various vintage Keithley instruments such as 147, 148, 181, 150b etc.
And of course its a crimped connection.
The back shell/housing/cap, call it what you like is a rather substantial thermal mass aluminium 'cup' filled with foam which is now disintegrating with age.
And that's it...!
I did say a quick tear down.