Years ago, a member with username Tyrant, sold original Jaguar controllers which he had modified with a (clicky) rotary knob.
It seems (to me anyway) that if you wanted a rotary controller, he was the man to buy from.
Then someone also started selling Pro controllers with a rotary knob on e-bay.uk, and there was talk about it here on AA because he used Pro's for that.
I recall another member with username Atari_Owl mentioned slightly concerned what a waste it was as he was developing a 3D game for the Jaguar with Pro controller support, and Pro's were not available in large numbers as opposed to the standard controller.
The last we heard was that this seller had some kind of serious accident and did not fully recover from that (therefore not mentioning his name).
Looking at the controllers in the e-bay listing it seems to me that those are the Pro's that he used to sell, although this auction is probably not from the person producing these back in the day.
Feel free to correct me if I am wrong