When enabled, mono mode for the A100 will convert the audio into a mono signal. Mono mode is ideal when sharing music or audio with others, as it allows everyone to hear the same thing, rather than there being a separate left and right audio channel.
The A100 will automatically switch to mono mode when only one ear bud is removed from the charging case. You can also enable or disable mono mode by selecting the slider in the app next to ‘Enable mono mode’.