article_snippet: Currently the unit of measurement is based on a metal cylinder - which should weigh precisely 1,000 grams - that is kept under lock and key in Paris.
article_snippet: But a metal cylinder - which should weigh precisely 1,000 grams - that is kept under lock and key in Paris is gradually losing mass, leading German researchers to look for a new formula to create the most accurate definition of a kilo.
article_snippet: The cylinder, which is meant to weigh exactly a kilogram, has a diameter of 3.9cm.
article_snippet: The cylinder, which is meant to weigh exactly a kilogram, has a diameter of 3.9cm.
highlights_snippet: Kilogram measurement is set from the highly-guarded metal cylinder .
  