Roller bearing that comes in two versions:

-X6: Thickness: 8.00mm. Inner diameter: 10.80mm. Outer diameter: 52.00mm.

-X8: Thickness: 8.00mm. Inner diameter: 14.32mm. Outer diameter: 48.48mm.

The gaps between parts are 0.20mm wide. You will probably need to loosen each roller a bit by hand after printing in order to make it work properly.

Note that one of the faces has its corners chamfered. That face must go down when printing.

As seen on the video, they work like they're supposed to.

https://www.youtube.com/watch?v=YiqpOM-MIWQ&feature=youtu.be