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.
Cubic Millimeters
A cubic millimeter is the volume of a cube 1 millimeter on each side, so 1,000 of them make a cubic centimeter. It is the same as a microliter, and a drop of water is roughly 50 cubic millimeters.