I have owned this caliper now for several years, and aside from going through batteries (they all do), this has performed flawlessly. I have compared this to a friend's Starrett and mine is dead on to the Starrett. I simply put, couldn't be happier with it.
The caliper was an excellent bargain, comparable in price to the Harbor Freight 6" stainless Steel Digital Caliper, but compared to the HF caliper, this thing is dead on like I said to the much higher priced Starrett. It came complete with a pretty decent case, a spare button cell battery, and a reasonably well written instruction sheet.
Use is pretty simple, bring the jaws together, turn it on and push the units (SAE or Metric), and then zero it. Once zeroed use the thumb wheel to roll it in / out and well, measure what you need to measure.
If you require prescision measurement in your shop, this is the tool to do that job!