The Fontainemelon 186-1-3 watch movement, also known as the Wehrmachtswerk in Germany, is often or always marked with the signature "6410" on its base plate. It is assumed that this is due to the various modules for the date or day/date function that are installed. The specific differences between the 6415 and 6416 are unknown, but it is likely that these designations relate to the different bridge shapes. The Fontainemelon 186-1-3 movement is a manual wind movement with a sub-second display. It has additional functions such as day, date (set by changing 22-24 hours), and a calendar feature. This movement was commonly used around 1950.