The slide caliper is a measuring instrument with a scale and a cursor that drift into it. It was designed to take external linear dimensions, by contact between two opposing sides. With less accuracy, it also measures internal dimensions, depths, bumps, among other.
The scale of this simulation is graduated in centimeters, which is divided into tenths (millimeter). The nonius divide the millimeter by twenty (1/20), marking the 0.05 mm (five hundredths of a millimeter).
To understand the science of measurement with vernier caliper, read and interact with the page: Vernier scale or Nonius - Reading and interpretation simulator: millimetric vernier scale, decimal precision – Metrology
horizontally drag and release the cursor
To zoom click in the magnifying glass "bottom of the simulator´s screen".
Scroll to the bottom of this page and see the caliper in inch simulators, micrometer simulators among others.