DT225 Trackball

The ITAC Mouse-Trak Trackball and the DT225 are the most smooth trackball. That is, they can spin.
〔see Trackballs That Can Spin〕
You can find DT225 Trackball online, going for about $300.

- https://youtu.be/tiRLZmqsOU0
- CH Products DT225 USB trackball
see also ITAC Mouse-Trak Trackball
Ball Size
DT225 trackball ball diameter is ~57 mm

