Korean fan clubs play an essential role in K-pop, their structure and operation is different from Western fan clubs.[225] Each club has its own name and color. For example, TVXQ fans are called "Cassiopeia" and their official color is "pearl red"; SS501 fans are named "Triple S" and their fandom color is "pearl light green"; and Super Junior's fan club is called "E.L.F." and they use the color "pearl sapphire blue".[225] Colors play an important role in fandoms, as fans express their unity and loyalty this way, especially in concerts where other artists also perform: fans from a certain fan club create their own sectors with the represented colors, usually with light sticks or official balloons and create a "Kpop Ocean".[225][226] If a color is already taken, fanclubs of new artists cannot choose them unless the color they want is taken by a soloist or a group of a different gender.[225] As colors are limited some artists do not have an official color, Big Bang fans for example hold crown shaped yellow light sticks, while Se7en's fans are represented by the number 7.