Plastic bag is ok.
Genuine one have very distinctive features.
For example they have an SR type battery Which is never installed.
Fake one have two CR type ones, one of which is installed and the other one inside a little blister which says SR44 but most of the time you're able to see the positive face of the battery with CR something written on .
The documents have a real pen scribed sign by the guy who did the quantity test.
And the cardboard box that contains the plastic case has no pictures of the caliper or whatever else.
Just Mitutoyo (the stripes on the upper left are parallel to the "y" longer leg and the "M" ), DIGIMATIC.
Now I can't remember exactly but the stripes should be grey and not black
Now I've got a fake one off eBay, they are not that bad just not worth to buy as you can get the genuine one fairly cheap from Mitutoyo website.
Last time I've checked the 150mm black digimatic was around 100 euro.
Coolant proof ones are a lot more expensive and I'm not aware about them being counterfeit
I've discovered that I've been not buying tools in a too long time, so...
Got 2 krino dies for cheap
1/2" and 3/4" NPT, 10 euro roughly each of them.
Then while scrolling on ebay, I came across this nice 600mm long 1/2" breaker bar for less than 10 euro as it was the last one of its batch
Couldn't leave it there.