the marks are known, the registration years are not
Marks that can be entered for this maker: Model, type or typology, Tang stamp / makers mark, Blade code, Era marker / packaging.
Nothing predates 1925; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: Archiving Industry — marks & tariffs