I have been trying to find out more information on this rare tank basculante but there has been little written on it. And if it was only for the French market, better still - more rare and collectible!! I love the tank basculante with the exception of the position of the winding crown which makes it a challenge to wind which is why I sold mine. But now with this ultra rare version with a small transparent case back, the search for one begins!! It is quite interesting that Hodinkee when comparing the watch with a Reverso concluded that the Frederic Piguet movement on the Cartier looked a lot better than the JLC movement