The Jamieson, 1 1/8 inch diameter, Jumbo Boring Bar needs to use the bent swivel holder. It has a tenon reduced to ¾ inch so it is compatible with the Jamieson stabilizing handle. The Jumbo Boring Bar allows deeper hollowing and stability while extended out over the tool rest. Large scale vessels up to 17 inches tall can be hollowed without vibration problems. The Jumbo Boring Bar is 20 inches long.