In 1943, Patek Philippe debuted the Calatrava Reference 1578, which remained in production until the mid-1960s. Available in yellow and pink gold and with either subsidiary seconds or sweep center seconds, it is distinguished by "spider" lugs that recall the chronograph reference 1579. The reference 1578 consisted of two separate movements. Early models utilized the caliber 12-120, which can be easily identified by its subsidiary seconds, whereas later models employed the caliber 27 SC, which features center sweep seconds. In the profile view, the dynamic nature of the angular "spider" lugs emphasizes the overall appearance.