Rio Cali 128 MB Sport MP3 Player 128 MB of memory for over 2 hours of MP3 or 4 hours of WMA music Secure Digital card/MMC expansion slot provides up to 512 MB of additional memory 5-band adjustable equalizer with pre-sets 18-hours of continuous playback with one AAA battery Compatible with computers with USB 1.1 ports running Windows 98 SE, 2000, ME, XP, Mac OS X