Kilogram (kg - Metric), mass
The kilogram or kilogramme, (symbol: kg) is the SI base unit of mass. It is defined as being equal to the mass of the international prototype of the kilogram. It is the only SI base unit that employs a prefix, and the only SI unit that is still defined in relation to an artifact rather than to a fundamental physical property. A kilogram is equivalent to 2.205 avoirdupois pounds in the Imperial system that is used in the United States.