The Girard Perregaux 27BF watch movement, similar to the ETA 717 movement but with lower specifications, is equipped with an early Incabloc shock device. The differences between the Girard Perregaux 27BF and the Zentra 295 movements are unclear. There are various samples of the Girard Perregaux 27BF movement that exhibit both bridge layouts shown in the archived records. The Girard Perregaux 27BF movement is a manual wind movement with sub-second functionality, and it was primarily used around the year 1935.