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 sense. The 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 featues 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. Reliable L plug for improved reliability and durability Straight, dual entry 4 foot cord Koss Spark-Plug: