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.
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.