Ca. 49mm, ca. 63g, 18K gold, super flat and elegant case, signed movement of the European Watch & Clock Co., no. 10549, top quality, Geneva striping, special fine adjusting device, chronograph with 30-minutes-counter, in excellent condition, silvered dial, original blued steel hands, in working order and in nearly new condition, absolute rarity. In the last 20 years only a few of these Cartier chronographs have been auctioned, to our knowledge none in this condition. A comparable watch was sold by Antiquorum in 1998 and was sold for more than 25,000 Swiss Francs.
https://www.barnebys.de/auktionen/objekte/488340695/pocket-watch-cartier-rarity-especially-large-extra-flat-cartier/