My only micrometer.

https://www.amazon.com/gp/product/B0...asin_title_o00
_s00?ie=UTF8&psc=1

Was planning to buy one of their new calipers, but my 0.0 mm resolution
Mitutoyo still works fine.

I need to know the dimensions of a rod, to stop guessing whether it's really
7.9 mm or actually 7.99 mm.

I would think such measuring devices jump to the next number when the zero
threshold is reached (going up) or crossed (going down). Will see!