The rare Cinelli EXA hexagon shaped handlebars whose idea came from the hexagon shape of a windsurfing boom according to "Cinelli, The Art and Design of the Bicycle"; this bar was a favorite of Claudio Chiappucci.
The special plugs to match are even harder to find.
Reminder: I invite you to contribute by sending in photographs of your
Cinelli bike, illustrations, personal stories, and articles about
Cinelli bikes and components. I can be contacted at firstname.lastname@example.org