Very rarely seen, this is a steel Cartier Tank Basculante Mecanique Ref. 2390 with a display caseback. Believed to be a Paris boutique special edition.

On the front is a silver guilloche dial with black printed Roman numerals and blued steel hands. When flipped over, its beautifully decorated manual wind Caliber 060MC is revealed through an open case back.

Only a small number of Basculante were produced with a mechanical movement (most came with a quartz movement), and an even smaller number were produced with a display back as well, which makes this watch extremely rare.