Linear Gauges are supposed to demonstrate a single measurement like temperature or battery charge, so they use not many elements as they are not necessary.
This gauge is a simulation of a radio scale which should be used as a radio station tuner. There are 4 FM stations and 4 AM stations, which are to be switched by clicking the appropriate labels. When a label is clicked, the station turns on and a warning about listeting for this station appears in the bottom of the chart. Above the station tuner you can find a station type tuner, so you can switch from the FM station types to the AM ones.