Question: What survival tool was hidden in the pants button of RAF pilots in World War II?
Answer: A tiny compass. It could be assembled from two separate trouser fly buttons that were part of the RAF uniform. The bottom button (see photos at the link) had a tiny needle in the middle that projected upwards. When balanced on the needle, the top button rotated in the earth’s magnetic field until the two luminescent dots indicated north. It’s true that if you were using the compass, your fly would be open, but that was deemed better than getting shot or captured.
