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 6inch in length) and delicate pots etc. The jaws also have a dovetail to mount small bowls (up to 6inch dia).