Pocket-sized signal mirror

Signal mirrors are used when you're stuck in the mountains or at sea, reflecting light to alert rescue teams and passing aircraft to your location. I've heard this item is US Military, but since there are no markings or other markings, I suspect it's civilian. However, the scratches and dents that show signs of use make it cool.

It's small enough to fit in a shirt pocket and is only about 1mm thick. It's made of a metal plate with a mirror finish, so it's not as effective as a mirror, but it can be used to check your appearance.