This could be viewed as nit picking maybe, I don't mean it that way. But hopefully some of this will help. To be accurate I guess it's a commonly used term by some, there's really no such thing as vernier digital calipers. Leaving the dial type out of this, there either a proper mechanically or laser etched and/or engraved vernier design, or there digital. It would be a complex design trying to manufacture a vernier/digital set of calipers and add a great deal to the cost for almost no gain. Fwiw Mitutoyo themselves are well aware of the now multi year and probably world wide problem of counterfeit copy's for at least there digital calipers showing up on sites like Ebay. Simply put there are NO cheap deals on there calipers anywhere unless they are counterfeits. There's also more than a few YouTube videos showing small but telltale mistakes on the calipers themselves, paper work etc to identify which might or might not be fake. Since those counterfeiter's change tactics so often and no doubt watch the exact same videos, the information becomes unreliable after a fairly short time if you want to be absolutely sure. Either buy from a well known reputable and trusted tool supplier or don't buy if you expect to get what your paying for. Even used on Ebay, Craigslist etc is no guarantee if the previous owner bought a counterfeit and is now reselling. I'd be surprised that doesn't happen fairly often when some finally do figure out they did buy a fake. So why is it always the Mitutoyo calipers that get counterfeited? For at least North America, there pretty much an industry standard in machine shops if you go by the number of recommendations for what to buy on forums like Practical Machinist. So the numbers being sold justify tooling up to produce those counterfeit's.
As biased as I am I still have to admit that just about any off shore set of digital calipers will now be accurate enough for anything a caliper is going to be used for. I do have a mid priced set I paid about $65 for some years ago I use for rougher work and minor wood working tasks. And maybe there's a few very high priced European digital calipers around I've never tried, Mayr etc. And there's some with apparent trusted names like B&S that I believe are now just rebranded offshore calipers with that B&S name slapped on them and a much higher price. But if any of them are any smoother or more accurate than the 6" Mit. solar powered ones I bought it really can't be by very much. While the internal circuitry has improved on some of those off shore calipers, it's still mostly unknown which brands have really done so or when. A lot of them still have very short battery life although using SR instead of LR battery types will last a whole lot longer. On average all the rest of my Mit digital equipment will get at least 3 or more years out of a fresh battery, Fwiw I've now spent over 40 years learning as much as I could about metrology as a side interest of mine. Many might not agree, but the real world facts are that no matter how good your calipers are, if your expecting anything closer than about .005" /.125 mm for actual accuracy and repeatability in average shop and measurment conditions your fooling yourself. Yes they can do a lot better than that, I've checked both myself, the mid priced set and the Mits against very good gauge blocks more than a few times. But that's under the absolute best of conditions and using Mitutoyos recommended method of gently squeezing the jaws against a known flat and square surface. I can usually get measurements averaging to within about .0015" on gauge blocks. But if I need and fully expect to be anywhere under that known .005" then it's time for a mike.
I see many on YT quoting the .0005" digit some calipers have like it has any meaning and more than a few wrong measurement techniques demonstrated like trying to get accurate measurements out on the jaw tips. Trust me that half 10th digit can be ignored, any digital calipers mechanical design, the small but unavoidable clearances required for them to even operate, and the allowable + - one count world wide standards for accuracy and repeatability as well as the rounding off within the tools circuitry makes that half 10th digit worthless. There's also enough changes and variables when measuring anything that random luck might even allow that last digit to even be correct sometimes, except there's no way to be absolutely sure when it is or isn't. So it then becomes a best guess situation and accuracy doesn't include any guessing.
There's also 3 industry standard terms used by metrolgy company's world wide that are non optional to fully understand once you go beyond a tape measure level of accuracy. And many seem to confuse them as meaning the same thing. #1 Resolution, or basically how many digits the tool has to the right of the decimal point. Just because it has multiple digits does not mean the tool itself is accurate and repeatable to that level because of the next two terms. #2 Repeatability, that's pretty much an indicator of the manufacturing quality and it's mechanical design the tool was made with so it can repeat to the same number with a high degree of confidence. #3 Accuracy, that's a combination of both the other two terms and how well the tool was made and it's smallest division it will reliably repeat to. None of these terms are interchangeable since none of them mean the same thing. So when shopping for any new measuring tool then it's stated in print repeatability and accuracy are the two most important specifications. There's also the additional issue of believing what's in print as being accurate. I've checked a few offshore produced items that sure didn't meet what the paper work said. A 4th much more complex term in metrolgy would be what's called uncertainty of measurement. Far better would be a Google search that will explain it faster and easier than I could here for anyone that's interested enough.
