The KSC21 Stereophone delivers a wide range frequency response while clipping comfortably over the ear. Soft, foam ear cushions guarantee an open, hear-through sound-perfect when you want to stay connected to your surroundings. Pivoting earplates provide a better fit than most clips.The KSC21 features dynamic elements for an extended frequency response from 50-18,000 Hz. Oxygen-free copper voice coils improve signal transmission and conduction for cleaner, clearer sound. Perfect for travel, the KSC21 includes a straight dual-entry four-foot cord, and a 3.5mm (1/8") plug.Built to last, the KSC21 is covered under Koss" Limited Lifetime Warranty - the only warranty of its kind in the stereophone industry. FeaturesFrequency Response: 50-18,000 HzDynamic element for extended frequency responseLightweight SportclipTM designFoam cushions for an open, hear-through soundStraight, dual entry 4 ft cord3.5 mm plug