The Longines 18.63 watch movement features a Girocap combined settings for the escapement wheel and an indirectly driven minute allowing a large balance. It was developed as a joint venture of several renowned brands, including Doxa, Ebel, Eberhard, Favre-Leuba, Girard-Perregaux, Juvenia, and Zodiac. It is worth mentioning that the calibres Felsa 4035 and 4036 may be considered equivalent, but their actual producer remains uncertain as they are not documented in any other register. The movement functions with a manual wind backwinder, includes the feature of backwinding, and was primarily utilized around the time of 1965.