How many?

Microinches

A microinch is a unit of measurement, the length of one one-millionth of an inch, equivalent to 25.4 nanometers. Being such a small measurement, micorinches are often used in precision machining and to measure surface finishes.

Hands

The hand is a unit of measurement of length standardized to 4 in (101.6 mm). It is used to measure the height of horses in many English-speaking countries, including Australia, Canada, the Republic of Ireland, the United Kingdom, and the United States. It was originally based on the breadth of a human hand. The average shire horse is 16 to 17 hands tall and can even reach up to 18 hands.