Rio One 64 MB MP3 Player 64 MB on-board memory; expandable up to 128 MB via SmartMedia cards Supports MP3 or WMA files; upgradeable for future music formats; PC and Mac compatible USB connection for fast file transfers Up to 10 hours' playback on one AA battery; accepts NiMH rechargeables Includes earbuds, AA battery, USB cable, and music management software