This 5 1/2" Set Gives You Both Straight And Rounded Calipers To Measure Just About Anything You Need To. Locking Screw Mechanism Assures Accuracy. 1 X Inside, 1 X Outside, And 1 X Divider. Adjusting Screw Is About 2", And The Knob Is About 1/2" To Make Overall Screw Size To About 1 1/2".