I used to have some of those. They're what we used before credit and debit cards, and there was actually a time when one of them would buy 20 candy bars (big ones, not "fun size"). I used to work an hour to get slightly more than two of them, and at the end of the day Uncle Sam swooped down and took a couple of them away to buy reliable Jeeps for the Army and "wanted" posters for the post office.