The Koss KHP21v are full-sized stereo headphones with closed leatherette ear cushions and an adjustable headband to provide comfort while blocking external noise and improving bass performance. The headphones feature anisotropic ferrite magnets which allows them to produce loud volumes even with low-voltage devices. They also feature oxygen-free copper voice coils which improve signal transmission for clearer sound. The KHP21v headphones have a 4 ft cord with an in-line volume control and 3.5 mm L-shaped plug plus 6.3 mm adapter. At only 6 ounces, they are lightweight compared to other full-sized headphones and are backed by a lifetime warranty. Like Koss' UR18s, the KHP21v headphones are designed to provide good sound while being lightweight and comfortable. They differ from the UR18s since they have a shorter cord in addition to an in-line volume control that the UR18s lack.