The Junghans 684.72 watch movement is an open face calibre that was introduced in 1919. It features a Breguet hairspring and incorporates a unique mechanism where the bent end of a slip-spring hooks into one of five notches. When the mainspring pulls the hook to the center, the slip-spring end jumps to the next notch, producing an audible snap that indicates the watch is fully wound. The movement offers functions such as stem winding and setting, with the option to include day and date displays. Additionally, it is designed for use in clocks and possesses an 8-day calendar function.