| 1 | A micrometer is one thousandth of one millimeter. | |
| 2 | One micron is a thousandth of a millimeter: a pinhead is about a millimeter across. | |
| 3 | They had an average 'retinal arteriolar' narrowing of 2.3 microns. | |
| 4 | The new big bang simulator is tiny - just fractions of an inch (20 micrometers) wide. | |
| 5 | Since then the researchers have reduced the bead' s size to about 250 micrometres. |