 The Duoplan led to the creation in 1929 of the world's still-smallest mechanical movement, the Calibre 101, whose 74 original parts (98 today) weighed a total of approximately one gram.The second family of watches equipped with the Calibre 101, Joaillerie 101 Étrier appeared in the 1930s.In 1953, Elizabeth II of England wore a Jaeger-LeCoultre Calibre 101 wristwatch for her coronation.