According to the records of IWC Schaffhausen, the present watch was sold in November 1931 to a retailer in Zurich.
Its movement is part of a series of 600 examples numbered 793'601-794'200 and produced as of 1924. The archives do not mention a specific caliber designation but the remark "réglage spécial" or "special adjustment".
It is thought that less than 20 examples of these display watches were made and sold to IWC's retailers until around 1942. This would also explain the large difference between the movement and case numbers, e.g. movement 793'669 and case 939'701.
A similar watch is described and illustrated in IWC-Uhren - Die "Schaffhauser" und ihre Geschichte by Reinhard Meis, pp. 146 & 147.