By making your custom split collet with a 5/8" outside diameter, this part can hold almost any tool you wish to adapt to it. A set screw tightens on the split collet to hold the tool in place. It is also used to hold the collet adapter, P/N 2085. The split face design with adjusting screws allows perfect centering of the tool's tip. Like the previous tools, it is designed for the machinist seeking every advantage in the quest for total accuracy. 1203 Sherline Adjustable Tailstock Custom Tool Holder Instructions