Convert from braccio [Italy] to gnat's eye

Unit Definition (braccio [Italy])
The Braccio is a traditional Italian measurement of length. The word means "arm", and a Braccio is approximately equal to the length of a man's arm, about 27 or 28 inches (68-71 centimeters). In modern times, the Braccio has become an informal metric unit of exactly 70 centimeters (about 27.56 inches), which is the same as the Arm Length unit.

Unit Definition (gnat's eye)
The gnat's eye is an idiomatic "unit" of distance; it's common to hear that something is "as small as a gnat's eye". In fact, the eyes of typical gnats tend to have diameters similar in size to a hair's breadth: roughly 100-150 micrometers (0.10-0.15 millimeters).