Convert from gnat's eye to hand [non-equine]

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 (hand [non-equine])
The hand is a traditional unit of distance, now used mostly to measure the height of horses. One hand equals 4 inches, 1/3 foot, or 10.16 centimeters.