DESC: A portable headphone is a headphone that is used on the go. This clip, behind-the-ear model by Koss is small, lightweight and features a titanium-coated, high-polymer diaphragm for accurate sound reproduction; dynamic element design for extended frequency response; neodymium iron boron magnet structures for deep bass performance; oxygen-free copper voice coils for signal clarity; and a straight, dual-entry 4' cord.