I'm older than dirt and actually used one. The glass face is round. That little dohicky under the three plays Quarters sign is a wheel The little cards you see through the glass have a list of ten songs each on each side. There are five cards total for 100 songs. To see the full list of songs you turn the wheel by hand to spin the cards to the next set of songs. There are little clips on the edge of the window that hold the cards open. Some of these were two sided so kids on both sides of a 4 seat booth could use them. Some were just mounted against the back wall of each booth. They were connected to the big Jukebox in the corner. Common brands were Wurlitzer and rockola.