These special 25mm extended jaws are designed to act like a pin chuck - expanding into a pre-bored hole. This is an especially useful technique for free form edge bowls. A real big advantage over Pin Chucks though is that you don't have to bore to an exact size - any size between the minimum and just under the maximum expansion will do.
The longer jaws allow for a very powerful spigot grip for all smaller work like lace bobbins (up to 150mm in length) and delicate pots etc. The jaws also have a dovetail to mount small bowls (up to 150mm diameter).
Jaw Travel Expanding - 26 - 46mm
Jaw Travel Contracting - 10 - 31mm
*Please Note - all sizes listed above are when jaws are mounted to the G3 or Supernova2 Chucks