That's the cylinder retainer and the horn ring contacts.
Look on the back of your steering wheel and you'll see where the spring loaded contacts rub, so you can turn the wheel and still honk.
Jim,
Lil'Red is a '87 F250 HD, 4.10's, 1356 4x4, Zf-5, 3G, PMGR, Saginaw PS, desmogged with a Holley 80508 and Performer intake.
Too much other stuff to mention.