2.25” with stylized illustration of a man’s face. Button was issued for a private event and reads in full “Studio 54/The Big 40/P.B.’s Party/1-22-78.” We don’t know who was having their Big 40 party but the event took place about 9 months after the club’s opening. Studio 54 was noted for open drug use and its celebrity patrons making it among the most famous New York City night spots in recent years. Very limited issue and essentially Mint. Only example we’ve seen.