These end plates lock into Solutech filament spools. They replace the end plates included in the repwinder kit.

One side includes a collar that goes over the barrel of the repwinder to make up for the larger hole diameter of the solutech spool. As well as a spacer on the outside to make up for the thin spool.

The only plates that I could find in the files they provide are for prusament and protopasta.

Of course you'll have to print out the remaining parts found here:
https://www.prusaprinters.org/prints/6174-repwinder-v2