Koss KDE250 Dual Element Stereophone (Black/Silver) Unique dual element technology-13 mm and 20 mm Side-firing 13 mm element produces crisp/clean sound, can be adjust to personalized angle 20 mm element brings high impact bass Connectivity Technology: Wired Unique dual element technology-13 mm and 20 mm Side-firing 13 mm element produces crisp/clean sound, can be adjust to personalized angle 20 mm element brings high impact bass Ear clip height adjusted by turning Custom Fit dial-3 size clips included Convenient carrying case for protective storage