Microliters
Microliters are a unit of volume in the metric system used to measure very small amounts of liquid. One microliter is equal to one millionth of a liter. This tiny unit of measurement is often denoted by the symbol μL. To put it into perspective, a single drop of water is roughly equivalent to about 50 microliters.
UK Barrels
A UK barrel is 36 imperial gallons (not to be confused with American gallons), about 163.659 liters or 0.163659 cubic meters. It is based on the traditional wine barrel used in the United Kingdom.