This is a universal joint which uses four 1/8 x 3/8-inch R2ZZ type minibearings mounted in the central ball. This turns more smoothly than a simple plastic pivot would. I printed in PLA on the Ultimaker 2. You can see it in motion below (sorry my output shaft was smaller than 6mm, so it was not centered in the joint)https://www.youtube.com/watch?v=rqXTtEzYYBk