The PMX80 Behind the Head Ear Speakers uses Vertical Ear Speakers and pumps rich audio comfortably into the ear. They are compatible with MP3, iPod and other portable devices with a 1/8 inch connector. The neck band system floats the ear bud for long lasting comfort. Sweat-proof coating wicks moisture, enhancing durability. Neck band features a reflective rear for safty when running at dusk. All Sennheiser Sport Series carry a 2 year warranty.