Most digital calipers have the same parts, controls, and buttons:

An on/off button

A zero button that sets the current reading to zero

A units button that switches between imperial and metric measurements, commonly written as mm/inch

A thumb screw that opens and closes the jaws

A locking screw that holds the jaws in place to keep the current measurement

Click here for a more in‑depth look at the different parts of digital calipers.