Not sure if these are same as I use....But learn how to use a vernier scale, it is quite easy.
These are a go to, tough tool for your tool box. They are great for quickly checking dimensional stock.
Mine were made in W.Germany (Yes, "West" they are that old...) I have never had to calibrate these (indeed they cannot be) and can check them against my machinists micrometer (+/-.0001") if necessary. They are precise to +/-.05mm or +/-1/64" (you can actually guesstimate to 1/128" but for that level of precision the micro's come out.
These are well worth the couple of dollars they cost.
Reviewed by: Christine from Massachusetts.