# Weights and Measures Act 1985, Part IV: Description of United Kingdom primary standard of the kilogram


The British copy of the prototype kilogram, being a solid cylinder marked “18” of height equal to its diameter made of platinum-iridium alloy (90 per cent. platinum, 10 per cent. iridium).

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Source: https://www.legislation.gov.uk/ukpga/1985/72/schedule/2/part/IV (the official version)
Page: https://openlegislation.uk/weights-and-measures-act-1985/schedule-2/part-IV
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.