2-9/16" with cutout on reverse where a name card can be insert to show through the clear celluloid center window on the front. Design includes lightning bolts symbolizing radio broadcast along with silhouette of conductor and five musicians. Text is "'You'll Like' Cotton Club Ginger Ale." Product took its name from famous nightclub in Harlem that operated during Prohibition and was famous for its great African American jazz musicians and entertainers of the era. The club was opened in 1920 by heavyweight boxing champion Jack Johnson. This button dates from the time period when Duke Ellington's orchestra was the house band from 1927-1931 and relates to radio broadcasts that originated at the club. NM, displaying Mint. Only example we've seen.