16 X 1″ Column with Hardware for Granite Checks ~ Fine adjustment. ~ 16″ long. ~ Accepts all AGD Indicators with lug back. ~ Fits part #’s 4401-0020, 4401-0021 and 4401-0019 Fine adjustment. Accepts all AGD Indicators with lug back. Fits part #’s 4401-0020, 4401-0021 and 4401-0019 16″ Long