.
Adaptor for a Sunpak 622 Flash Unit.
They don't seem to be embarrassed by the fact that the original new label is still
showing $11.95, but now, used, they want $74.69 (plus $160.37 shipping to me).
They don't seem very rare - there are several on Ebay right now.
This is an adaptor that plugs into the flash unit body with a socket to receive
510v from an external battery. I don't think there are any electronics inside.
For some reason Sunpak did not simply put the 510v socket directly on the
flash body like they did for their other units at the time.
RARE Sunpak CV-1 Conversion Adapter for Auto 622 Pro System #G920 | eBay