What is (just) one example of a physical object other than Federal Reserve notes, gold or silver certificates that could be chosen by a group of people to use as money (a medium of exchange) in the United States today? Please explain do not use the example Gold, silver, Gift card, electronic benefits transfer card, gift card.

Please demonstrate your understanding of how what you have chosen could have the function of money known as a "Unit of Account" (with two different numerical prices), as it is described ?"