Sony Walkman 4GB Headphone-Integrated NW-WS413 (Black) 4GB Sports Wearable MP3 Player, Waterproof: For use in salt & fresh water up to 2-meters deep, Sweat resistant, dust proof design endures through the toughest training conditions Ergonomically designed for a secure fit and long-lasting comfort, Ambient noise function so you arent isolated from the world around you, Up to 12-hours playback Drag & drop from iTunes for Mac or Windows, Playback MP3, WMA, AAC, and Linear PCM Audio Files, Supplied: USB dock, regular & swim earbuds (1set each), adjustment loop, Hi-Speed USB 2.0