The Junghans 640.01 is an open face calibre watch movement, featuring a bimetallic screw balance and a Breguet hairspring. It incorporates a lever with hidden pallets and counter weight, along with a barrel equipped with Geneva stopwork. Although there is uncertainty surrounding its origins due to the overwritten Landeron signature, it is preliminary listed as potentially being an Alpina and Landeron collaboration. The movement operates through stem wind and pin set mechanisms, includes a sub second function, and offers a timer function. It was commonly used during the period around 1895.