I believe these can hold 1/2 3/4 7/8 1 and 1 1/8 by measuring. LATHE TOOL POST engine turning BORING BAR HOLDER WILLIAMS No 1-B Machinist. The item "LATHE TOOL POST engine turning BORING BAR HOLDER WILLIAMS No 1-B Machinist" is in sale since Monday, September 13, 2021.This item is in the category "Business & Industrial\CNC, Metalworking & Manufacturing\Workholding & Toolholding\Toolholding\Adapters & Holders\Lathe Turning Tool Holders". The seller is "claas900" and is located in Appleton, Wisconsin. This item can be shipped to United States.