Starrett 190D - Little Giant Jack Screw - Auxiliary Pointed Screw with Fine-Adjusting Screw
The Starrett Little Giant Jack Screws are very handy for leveling work on planer beds, upright drills, setting up machinery, and for general use in the toolroom or machine shop. 190 and 191 have 20-pitch screws and for those who desire a finer adjustment, the F190 has a 40-pitch screw.
190 Series Range: 2-1/4 to 3-3/8in (57-85mm)
191 Series Range: 1-1/2 to 2-1/4in (38-57mm)