Convert from gnat's eye to fod

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).

Unit Definition (fod)
The fod is the traditional Danish foot, equal to about 12.365 inches or 31.41 centimeters.