51 Crosstown Rivalry USC vs UCLA pin w/ ribbon

This is a pin and ribbon from the 1981 game between USC and UCLA.   The Pin says UCLA vs. USC.   It also has a ribbon attached to it, that says "51st annual cross town rivalry.  USC vs. UCLA.  I was there, Nov. 21, 1981"  The pin is 3.5 inches across, and the ribbon is 6 inches long.