The Girard Perregaux 77 watch movement was produced between 1888 and 1906, with approximately 97,680 units manufactured in that period. It is an open face calibre and features a bimetallic screw balance with four adjustment screws, as well as a Breguet hairspring. The movement is equipped with a barrel that incorporates Geneva stopwork. The IWC 52 19'''H5 serves as a reference for further details. It functions through stem wind and pin set mechanisms, displaying sub seconds.