Le Grand K is a platinum cylinder that serves as the standard for measuring the kilogram. It was created in 1889 and is kept at the International Bureau of Weights and Measures (BIPM) in France. This cylinder is made of a platinum-iridium alloy and is precisely defined to represent one kilogram. In 2019, the definition of the kilogram was updated to rely on physical constants rather than a physical object. However, Le Grand K remains an important historical artifact in the field of metrology, symbolizing the evolution of measurement standards over time.