A CF card is a compact flash memory card. It's rectangular and has two rows of holes along one side which fit over the connector pins when you slide the card into its socket. Compact flash cards can be bought from electronics or photographic shops, and some department stores. They are not expensive but these days they are usually 1Gb and up. The TASCAM Pocketstudio 5 can only format up to 128Mb so most of a modern card is not used but the card will still work.