Summary

This tag is 20x20 in size and used to test filament change.
Depending on your slicer, choose the layer that the filament will be changed. then slice again

Super Slicer has its own slide bar on the right to add M600 (Filament Change), a maximum of 5 times changing filament
Cura on the other hand, you will need Post Processing G-Code Plugin (Pictures as above).

Both work well with Marlin but Klipper doesn't.

In order to use Filament Change for Klipper, go to Sample Macros, slide down to [G-code_Macro M600] and add the script to your printer.cfg
link: https://github.com/Klipper3d/klipper/blob/master/config/sample-macros.cfg

Or you can watch this Youtube guide on how to use Filament Change for Klipper:
https://www.youtube.com/watch?v=RUJ6D-N37k4

And Happy printing