Even though it seems like most people in the world have spent recent years mining for cryptocurrencies like Bitcoin, you'd do better to keep all your bottle caps. After all, the Fallout video games have shown us that after the nuclear Armageddon, people will use these pieces of metal as a method of payment.

The Fallout 4 Nuka Cola Keychain will allow you to always keep a reserve fund right in your pocket in case you need to buy some Stimpaks or Rad-X. Or some Iguana on a stick, if you like that kind of stuff... ;)