The Girard Perregaux 31.5 watch movement is an early bumper automatic movement that was a redesign of the Harwood automatic. It is based on the 8.75''' manual wind calibre AS 612, which served as its foundation. The movement is commonly referred to as the AS 1049A, with its main distinguishing feature being a common train bridge. It features an automatic (bumper) mechanism and does not include manual winding. Additionally, it has sub-second functionality and is available in both sweep seconds and non-sweep seconds variations. The movement was utilized during the period of approximately 1935.