The Dugena 638 watch movement is similar to the ETA 717 movement, but with a lower position and an early Incabloc shock device. The exact differences between the Zentra 185 and Dugena 638 are uncertain. Most samples of the Dugena 638 movement feature two bridge layouts, as shown in the archive. However, there are also samples with different bridge layouts. The Dugena 638 movement functions include manual winding, sub-seconds, and Incabloc Shock Protection. It was used during the period of approximately 1935.