Koss Lightweight On-Ear Classical Arc Headphones, RUK40K: * Lightweight on-ear stereophones * Dynamic elements deliver smooth bass and a wide frequency response * Uniquely designed cushioned pads for ultimate comfort * Pivoting ear cups * Available in an assortment of colors * Flat, dual entry 4" cord with 3.5mm plug * Frequency response: 20-20,000Hz * Impedance: 36 ohms * Sensitivity: 98dB SPL * Color: black