I experienced problems with the TPU / FLEX filament being pulled out of the MMU unit when I used my automatic rewind filament holder. That's why I made this one. It "curls" the PTFE tube so that a resistance is given so that the TPU / FLEX filament has a greater friction, which prevents the filament from being pulled out of the mmu unit. There are two models one almost straight, the other has a slight curvature, they should fit most setups.
The author hasn't provided the model origin yet.