What I wonder, is how is one sure that a gauge, be it cheap, or a more expensive one, accurate? I once read that the digital ones are the most accurate. I have a digital, and a mechanical analog one, and a couple pencil gauges. I had more, but a I started checking them against one another, and threw out the ones that gave readings that varied more than 2 lbs from the others. Even so, the remaining ones don't all read exactly the same, but within 1 or 2 lbs, so I guess that is close enough.