The flash drive used for square dancing is the same as a regular flash drive, so you can buy a regular flash drive and just download the music used for square dancing.
The name "USB flash drive" first came from a new type of storage device produced by Lanxess, called "USB flash drive", using the USB interface to connect. After the production of similar technology due to the device has been registered patents and can no longer be called "USB flash drive", but instead of the harmonic "USB flash drive" or image called "flash memory". "Flash drive" and so on.