We have a few of these wartime guides to military insignia, aircraft spotting and the like. I've shown you one or two before. This one was printed for the The Home Life Insurance Company of America. There is a Home Life policy for every purse and purpose!
The disk on this one is 4.25 inches. The length from top to bottom is one inch longer. This one isn't in great shape. The lower left corner is close to tearing off. The copyright date is 1942.
You can identify all the pins and uniform patches for the Army and Navy with this wheel. I love the pin for the ordnance specialist. It looks like a pineapple. The engineer's symbol is still used by the Army Corps of Engineers today. I don't suppose they have much reason to change these.
I didn't realize you could still serve in the Army with only one arm.