Nothing wrong with the metric system, we do use it quite abit here. Plus most of the inch rulers are based on the english ruler 1/4, 1/2 , 1/3 and on.

Also most measuring devices nowadays in the U.S have both metric, and standerd.

Look close at the pic of the calipers, it has a button to change the units of measurement to either mm's or inches.

I have worked most of my adult life as an auto tech repairing european cars, life is so much easier working in millimeters.