If the unit includes a removable memory card slot, then it allows you to load maps, digital photos, MP3s, and possibly other digital media files using a removable digital media cards such as an SD Card. Often times, you can expand on the typically small memory card included with the unit and purchase a higher capacity memory card that stores more data. Removable digital media cards include SmartDigital™ (SD), MultiMedia Card (MMC), TransFlash™, and Memory Stick®.