In this photo taken Wednesday, Oct. 17, 2018., a replica of the International Prototype Kilogram is pictured at the International Bureau of Weights and Measures, in Sevres, near Paris. The golf ball-sized metal cylinder at the heart of the world's system for measuring mass is heading into retirement. Gathering this week in Versailles, west of Paris, governments on Friday Nov. 16, 2018, are expected to approve a plan to instead use a scientific formula to define the exact weight of a kilo. (AP Photo/Christophe Ena)
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