It is definitely imperial sizes only. You can tell that as it only has its sizing in quoted in inches.
I mess with the Americans at work, by asking for a metric snifter. First I show them what a shifter is, then show them the sizing on the handle. If it has only inches then it can only be used imperial fasteners. If metric sizing, then only metric fasteners, and if it has both then it can be used on either. And if anyone believes the last sentence, then I do have some great beachfront property in Kansas to sell you!