This is a replacement for the standard roller mount - the part that holds the belt bearings to the roller - which creates a mounting point for a cable chain at the bottom of the roller.

The cable chain I use is this one:

[https://www.thingiverse.com/thing:3117461](https://www.thingiverse.com/thing:3117461)

I expect other chains are suitable. The hole spacing matches the ends of the above chain.

Print large side facing down.