Errrr - WHAT???Not sure if these are pro caliber or not, but they're acceptable as far as calipers go.
"calipers" have NO use in finish work. There ARE tools to measure wet film thickness, but it's better to follow directions, read, study - then apply the whole system on scrap wood until you get it right.
There are no shortcuts, and if you follow directions about applying THIN coats, not worrying about coverage at all (it happens on its own) and don't TOUCH the guyitar until you know what you're doing it should come out at least "OK"