This is a small device that is designed to clip into the Bambu reusable spool to ensure that it is correctly locked together and cannot accidentally come undone, causing untold headaches (as I learnt to my cost).

I made this as I recently had an occurrence of such a problem and decided it would be better safe than sorry.

The orientation it is printed in does not give the best finish but it is the strongest in the plane that is most important and you do not want the lower half of the tab breaking off.