Prior to the 2019 redefinition, what physical object defined the standard for the kilogram?

Answer

International Prototype Kilogram (*Le Grand K*)

Previously, the kilogram was defined by the International Prototype Kilogram, referred to as *Le Grand K*. Laboratories compared their standards against this physical cylinder.

Prior to the 2019 redefinition, what physical object defined the standard for the kilogram?
measurementsystemunitstandard