That is for standard 100mm masterspools refills. It is fitted to have that "bounce" feeling when picking the right one
I used it with fiberlogy refill spoll
You can use also “note” project to attach your description to the separator. here:
https://www.printables.com/model/876611-note-description-for-master-spool-filaworks
The author remixed this model.
Changed inner diameter to standard 100mm
Removed inner parts.