I just bought a lot of audio-related components at auction from the estate of someone who used to repair/build audio equipment. There are a pile of these things and I have no idea what they are. Anyone have any ideas?
I was thinking the same. Ohm it out, if it seems to be a straight connection from terminal to terminal, its a pass-through for use between parts of a chassis.
It is a ceramic feed through - normally soldered into a hole in a metal chassis to pass a connection through. Used a lot in RF high frequency circuits.
Sometimes they include an integral very low value inductor and capacitor for filtering purposes.