Convert from t'sun to gnat's eye

Unit Definition (t'sun)
The t'sun is a Chinese unit of distance equal to 0.1 ch'ih or about 1.41 inches (3.58 centimeters).

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).