authority once told me, many mechanical watches have similarities. I mean they all have springs, jewels, barrels, plates, and escapements. Kind of like people, if you get enough of them, some will look the same. So although I do not know for sure, and have heard it a lot, I assume the only person that knows Is Mr. Dufour himself, and I bet he is not talking. This may be one of horologies unanswered questions.