Wes wrote:

No, there are 4 adjustment screws on the mounting plate that allow you to after loosening
the clamping bolts to center the chuck body on the base plate then secure the clamping
bolts.

All the eaze of a 3 jaw with the accuracy of a 4 jaw independent. Very nice setup, I use
one at work from time to time.

You may not get perfect repeatablity on a single diameter but you can dial in any chucked
up part to your level of perfection.

Wes