A Portable headphone is a headphone that is used on-the-go. When used in your iPod or other portable player, you want to match superb sound with absolute comfort. That"s when the Koss Spark Plug stereo earphone makes senseThe SparkPlug features a dynamic element that is positioned just outside the ear and connected to a tubular port structure that is inserted on a soft expandable cushion into the ear canal. The soft foam cushion expands for a custom fit to improve isolation and enhance deep bass and treble clarity. Now with improved slow memory ear cushion made of hydrophillic, formed urethane, you are guaranteed a custom fit every time. Ths SparkPlug also features a white cord to compliment many mp3 players. The fit enhances isolation when you want to plug out ambient sounds that interfere with the listening experience. The SparkPlug has a frequency response performance of 10Hz-20,000Hz and full Sound of Koss. Combined with your favorite music and a portable sound system, it is the ultimate accessory on the go. Built to last, The SparkPlug is covered under Koss" No-Questions-Asked Lifetime Warranty - the only warranty of its kind in the stereophone industry. Straight, dual entry 4 foot cord.