Selling it as 3700 but I couldn't get the caseback open to see inside as I don't have the right tool. I'm guessing it as this has the first generation bracelet and the early dial design without IWC logo. The watch works fine. The date doesn't change until around 12:40am and the stop button is a little stiff but works fine. Bracelet fits up to about 19mm. Comes with box and papers but no guarantee card.