A prison guard's last line of defense used to be his key!

In the world of self defense, people have a lot of options, both from the lethal and non-lethal field. Some will alert others to come for help, some will incapacitate an attacker with pain or discomfort, then others with leave them dead. But how did people like prison guards defend themselves back when the choices weren't around? The answer: gun keys.

These were small cell door keys, probably decorative and non-functional, that doubled as a single-shot pistol.

Granted, the pistols and their ammunition were far too small to be considered lethal—but chances are it would stop a hostile inmate in their tracks. Of course, an actual pistol would have been far more intimidating and effective as a weapon, but it's must have been nice for a guard to have a plan B in case a prisoner gets a little rowdy or steals their primary weapon. Plus: That is some really cool miniature engineering at work!

(Source)