Little Giant Jack Screw, 2-1/4 - 3-3/8" (57-85mm) Range, 1-1/4" (32mm) Base Diameter. Little Giant Jack Screws are used for leveling work on planer beds, drills, setting up machinery, and general use in toolrooms or machine shops. 190 Series are 2-1/4" to 3-3/8" / 57-85mm in Size. Series 190 and 191 have 20-pitch screws and for those who desire a finer adjustment, the F190 has a 40-pitch screw. Jack Only.