This 14" Set Gives You Both Straight And Rounded Calipers To Measure With Inside, Outside, And Divider. Locking Screw Mechanism Assures Accuracy. Adjustable Screw Is About 3" Long And The Knob Is About 1/2" To Make Overall Screw Length Of 2 1/2". Outside Caliper Opens To About 11 1/2" Max. 3 Pieces In Set 14" Long Both Straight & Rounded Measure Inside & Outside All Metal Construction