How many?

Micrometres

The micrometre or micrometer, also commonly known as a micron, is an SI derived unit of length equalling 1×10−6 metre; that is, one millionth of a metre (or one thousandth of a millimetre, 0.001 mm, or about 0.000039 inch). The micrometre is often used to measure the thickness or diameter of microscopic objects, such as microorganisms and colloidal particles.

Yards

The yard is an English unit of length, in both the British imperial and US customary systems of measurement, that comprises 3 feet or 36 inches. Did you know that a yard of ale, whilst being 2.5 imperial pints of beer, is so called because the glass is a yard long.