A very nice Jaeger LeCoultre Futurematic in rose gold, 18 carats, automatic, with no visible crown. Size is 37mm. Caliber 497, reference 501. Calibre 497 debuted with the Jaeger-LeCoultre Futurematic Ref. E 501 and was much more advanced than the earlier Cal. 476/Cal. 481. It features a larger balance for improved accuracy and hacking seconds. One unique feature is a lock that holds the swinging weight in place when the mainspring is fully wound. It also features a special 6 hour power reserve, allowing the watch to immediately function when it is put on, rather than requiring it to be wound first. The Calibre 497 featured a power reserve indicator along with small seconds located at the unusual position of 3 00. Approximately 52,500 examples of Calibre 497 were produced between 1951 and 1958.