Semaphore Trainer, US Navy
Here is a very interesting device, a Semaphore, or Flag Signaling, Trainer, made for the US Navy Special Devices Center by the advertising promotional firm Einson Freeman, Inc.
The device is a rotating training card within a card. The "Sender"- view is on one side and the "Receiver"-view on the reverse side. When rotated to the desired letter by the Sender, he see's which flag/arm position must be taken to communicate that letter. The Receiver, upon observing the flag/arm positions, can interpret them by rotating the card to match the arm position being observed, therefore obtaining the letter.
Measures ~4 inches square. In terrific condition given its age.