The Futurematic is one of Jaeger Lecoultre's icons, indisputably. The Porthole version, ref 502, is very alluring with its futuristic signature and these 2 portholes, one for the power reserve, on the left, and the other for the seconds, on the right.
And while we are at it, here is a second Futurematic, Ref E 501, I took in picture in Paris some years ago, with an unusual dial.