You can get them in all sorts of varieties now, dial, digital, and the original type shown the the picture.
Although if I were being a pedant I would have to say that only the pictured type is a true
vernier caliper.
Named after Pierre Vernier who invented it sometime in the 1500's
The dictionary definition goes something like this;
"A small, movable auxiliary graduated scale attached parallel to a main graduated scale, calibrated to indicate fractional parts of the subdivisions of the larger scale, and used on certain precision instruments to increase accuracy in measurement."
Err.... Sorry about that.
I'll get my coat!