Earbud-Free Bone-Conducting Audio, Remain Aware of Your Surroundings, Integrated 4GB MP3 Player, Up to 8 Hours of Playback, Swim-Friendly IP68 Water Resistance, Supports MP3, WMA, FLAC & More, Integrated Controls, PremiumPitch 2.0+ for Powerful Bass. Swim laps to your favorite motivating music mix with the Xtrainerz Open-Ear MP3 Player Swimming Headphones from Aftershokz. These headphones are rated IP68 so they can be submerged for use in the pool. The full wraparound titanium band is designed to slip easily over your ears and under your swim cap. Nothing goes in your ears as bone-conducting technology transmits audio via vibration. This lets you listen while still being aware of your surroundings. The Xtrainerz are not Bluetooth compatible and require no additional devices. Audio is played back through its built-in 4GB MP3 player. Use the included USB induction charging cradle to connect the Xtrainerz to your PC where you can conveniently drag-and-drop audio files onto the headphones. The 4GB of storage is enough for hundreds of tracks in MP3 WMA FLAC WAV or AAC formats.