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.
US liquid gallons
A US liquid gallon is a volume measurement used in the United States for liquids such as water, gasoline, and milk. One US liquid gallon is about 3.78541 liters. A standard bathtub is about 80 gallons of water and a car gas tank can hold anywhere between 12 and 20 gallons of gas.