Cal. 497 and 827
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.
Calibres 817 and 837
Calibre 817 was used in the Futurematic Ref. E 502 from 1956 and was a modification of the existing Calibre 497. Like that movement, it has a power reserve indicator at 9:00 and small seconds 3:00, but in Cal. 817 and Cal. 837 these are tiny round windows rather than being full subdials. The power reserve uses a paddle-shaped indicator attached to the catch for the bumper rotor. It was a much-simpler display, half white and half red on Cal. 817 and black and white on Cal. 837. And the seconds disc has a simple arrow and no other markings.