It’s simple. Who would suspect the little nickel of hiding a secret? Though… come to think of it, it is a little suspicious that you carry any change on you at all these days.
- Secret interior compartment
- Can’t open the coin without the supplied opening device!
- Indistinguishable from a regular coin to the untrained civilian eye
Also available in British pound, Euro 50 cent, and Aussie 20.
https://www.youtube.com/watch?v=c7C-ScHMKc8