Bluebuds X have been designed and developed with every ideal in mind. Wireless Music+Calls coupled with Superior Audio Performance, a revolutionary 8 hour battery play time, Patented Secure Fit for Sports, Sweat Proof Nano coating locks moisture out, and the all new X-Fit, you have the option of lifting the cord off your neck for the perfect workout headphones. As the Official traning Headphone of USA Triathlon, you can be confident knowing you are selecting a trusted and proven sport headphone