A split 5x7 keyboard with 3 thumb keys. Made by Unikeyboard.
Make example for this keyboard (after setting up your build environment):
Or for the Workman layout:
Reflashing the stock firmware is pretty easy. Just follow the same steps in the original guide. You will have to manually reset the Pro Micro (by shorting the GND and RST pins) during the upload step. Then reapply your keymap through Arbites.