Morton Machine Works Quill Stop part 1220-S. 1/2-20 Thread Stop Rods for Bridgeport Milling Machine. Accurate Adjustment to 0.001″. This device allows you to make quick and accurate adjustments of Stop Settings. Used with existing stop screw, it fits all 1/2-20 thread stop rods on Bridgeport milling machines. Simply depressing the push button moves the nut without turning to your desired stop position. Turning the nut enables you to fine adjust to within 0.001″ by rotating the graduations on the nut. Micrometer adjustmentEasy to use