A. Lange & Söhne

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You need to buy two. One for each wrist. You won’t need to do any delt work at the gym. Of course a gym membership is less expensive.

A bold and audacious concept (as with the Double / Triple Split, the Zeitwerk...), including the ratchet-key wind. An amazing feat of German engineering - stacking two 6-foot long mainsprings and funnelling all that energy through a remontoire. But mostly... 

Great description Aviya. I’ve always loved the clean look, but probably too impractical and a bit expensive.

As you likely know, the winding key is actually a miniature torque wrench with a planetary-geared slip that prevents you from over-winding the watch. Really quite ingenious.

And as others said, that R&D eventually led to the zeitwerk. I think it will be fascinating if one day Lange revisits the complication in an wearable format.

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Apart from that it is a monumental (pun intended) collector's piece, that I would love to own!

...but the watch isn't wearable for me. Makes me admire the Twin Beat even more.