Cubic Millimeters
Cubic millimeters are volume units in the metric system. A cubic millimeter is a unit of volume equal to the volume of a cube with sides measuring one millimeter each. It is a very small unit of volume commonly used to measure tiny amounts of liquids or solids. For example, a single drop of water may have a volume of approximately 50 cubic millimeters.
US federal barrels
A Federal US Barrel is 31 gallons which is about 117.35 liters. This unit is normally used for apples, potatoes and other agricultural products.