The HD251 has an integrated volume control on the cable allowing you to adjust the level without taking out your music player. With its ergonomic shape design, the HD251V is optimized for MP3, CD, music phones, and portable media players. Its dynamic speaker system has powerful neodymium magnets for a clear, transparent, and powerful bass audio reproduction. Put on the HD251V and enjoy your music while you are working, walking, or relaxing at home.