Bone-conducting technologyListen to music underwater without blocking your ears with the Aftershokz Xtrainerz Waterproof Sports Headphones. Their open-ear design uses bone-conducting technology to send sound directly to your inner ear. No earbuds means no earphone-induced swimmer’s ear.Sports designThe Xtrainerz were designed with sport in mind. Lightweight, wire-free and waterproof for up to 2 hours, they’re ideal for swimming, triathlon and other in-and-out of water activities. With your ears completely open, you can hear what’s going on around you – but with a soundtrack of your choice.Built-in MP3 playerLeave your phone at home or in the locker. The Xtrainerz have a built-in MP3 player with 4 GB storage for up to 1200 songs, so you don’t need to carry other devices while you train. Just transfer audio files onto your Xtrainerz at home and you’re ready to go.