It's thinness, thinness, strength and the best usability of the tip. Although it is the only difficult point that it is slightly rustable when salt adheres as a material, it is a wrench that can cover it with other merits.
For ordinary wrench it is convenient for tightening the nut where there is thickness and does not enter. There is less backlash, so there are institutions so it is safe. However, there seems to be little worry about durability in appearance, but ,,,,, (laugh)