I found this after this answer on Quora:

In the past, someone told us what was on paper money, & we folded different bills different ways. Now, there’s a tiny talking machine with a slot to slide the bill in, & a button on either side that we press to hear the denomination. I don’t know what it’s called, but this device fits in my wallet, & increases my independence considerably. It’s also helpful to people who go blind later in life, & have trouble learning Braille. I still fold my bills after it reads them to me, but this machine allows me to be sure that I have the right amount of money.