Walsoon WS531 Waterproof Underwater 4GB MP3 Music Player+FM Radio for Swimming Waterproof MP3 player is tailored for swimmers and water sports enthusiasts. The waterproof earphone attaches to the player via a special screw-in jack to keep the device water-tight. The waterproof earphone employs a special non-woven fabric membrane to keep the speaker vibration plate dry while maintaining a high quality sound output. The new stylish headphones perfectly match the ergonomic principle therefore. With FM radio function.