Chain keeper for rear hub 130 x 5 mm QR.
This chain keeper has 2 parts, both mounted for transport and disc only during maintenance or cleaning.
Remove the bicycle wheel and Quickrelease (QR) and mount the chain keeper on the quickrelease.
Check also my other designs: https://www.prusaprinters.org/social/201278-hans/prints
The author hasn't provided the model origin yet.