I've had a few different versions of "Pocket Signal Disks" along the lines of this one, and will always grab them when I find them as who knows when knowing morse code and semaphore might come in handy???  This one dates to WWII and features two arm semaphore on one side, and international morse code on the other, with dials turning smoothly to show an array of flags, codes and signals. A cool thing, and if not to be used to actually practice one's signaling methods, perhaps inspiration for some sort of party game!

Double sided, in original Pocket Signal Disk envelope. Disk measures 5 7/8" x 3 3/8". Envelope: 6" x 3 5/8".All in good shape, with the dials turning smoothly.