this is an adapter spacer for Polymaker's .75kg spools to fit on Bambu's reusable spools.
Add my print to this linked print https://www.printables.com/model/331971-polymaker-cardboard-to-bambu-spool-adapter
be sure to carefully rip cardboard from the spool, after securing the filament with painter's tape.
The author marked this model as their own original creation.