Various modes, can be switched (using Adjust layer and the selected one is stored in EEPROM.
Modes for Qwerty and Colemak support
Modes for Mac vs Linux/Win support -> different order of modifiers and different action shortcuts on the "UPPER" layer (the red one in the image). Designed to simplify transtions when switching between operating systems often.
The OLED on master half shows selected mode and caps lock state and is rotated.
Left encoder controls volume up/down/mute. Right encoder PGUP/PGDOWN.