WW2 RAF Uniform Buttons Becomes A Compass?!

These are buttons from the WW2 Royal Air Force (RAF) uniform, specifically the trouser fly buttons. When you stack both of them on top of each other, they make a mini-compass, for use if you get shot down behind enemy lines. How this compass works is: The bottom button will have a needle in the middle that points upwards, and when the top button is placed onto the needle, the top button will rotate due to the earth's magnetic field where the two radioluminescent dots indicate north while the single dot points south. Such a genius design!