English: Two wrenches, both nominal size 5/8", with a diagram superimposed to show the logic that allows them both to be nominal size 5/8" when their actual sizes are clearly different (across-flats distance vs screw diameter). The across-flats definition is the common standard today, and has been for many decades. The larger wrench in this photo is from the 1920s or earlier. Its face was polished to allow the size stamp to show well in the photograph.