This Hercules string display made of metal is from the 30s and is uber rare.
Hercules is a brand which diseappered in the 40s and little is known about it. Distributed by Progressive Musical Instrument from New York NYC. Not related to Hercules brand distributing guitar stands.
It is supposed to be placed on music shop counter. Glass front on the customer’s side and back on the dealer’s side.
Back can be opened to fill in or get string packs.
The look, shape and design is typical from the Art Deco era.