The Parrenin 641D is a mechanical watch movement that was in use from 1932 onwards. It features an open face calibre design, with a pin-lever escapement and coarse imitation of balance screws. The movement includes a ratchet mechanism on the dial side, along with a crown mechanism that utilizes a rocker bar. The J69F is commonly or always identified by the signature "J69." This movement is capable of stem winding and setting, as well as displaying a sub-second function.