This model is for converting a Print Bed cardboard spool to a Bambu Lab spool. This is done by tearing the sides off the core and inserting the spacer into the core so it fits in a Bambu reusable spool (for example the ones that come with an AMS, etc.)
Here is how it works:
I did it a little backwards, but the spacer can really go on either side of the spool, just depends which side you take off first. It works better if you remove the color side first (the one I did last in the video) in my opinion.