The Fontainemelon 90 watch movement is a hunter calibre with a distinctive crown mechanism featuring a rocker bar and a ratchet on the back side. It includes a crown wheel that serves no operational purpose and a likely left-handed ratchet-wheel screw. The movement variations, such as the 231 and 661, mainly differ in terms of bridge shapes. The Fontainemelon 90 movement incorporates the following functions: stem winding and setting, as well as sub-seconds.