The Starrett 196 Universal Back Plunger Dial Indicator features graduations to .001" and 0.02mm that handle by far the majority of jobs. Shank diameter is 1/4" (6.3mm). Antimagnetic models are also available – (inch reading) 196A6Z and 196B6. For full use, the operator first chooses the proper contact from the three hardened contact points that come with each model. Then the contact should be brought against the work with enough pressure to give the hand one full turn. Set the hand at zero by rotating the dial with the knurled bezel. This provides one full rotation of the hand both to the right and left of zero, showing a rise or drop in the work and the amount of that variation. 0-100 with 3 Contact Points, Adapter, 4 Attachments in Case This provides one full rotation of the hand both to the right and left of zero, showing a rise or drop in the work and the amount of that variation.