Extra-large 16 mm drivers make Sony's MDR-ED21LP Fontopia Stereo Headphones an outstanding choice for listening on the go. Fitting snugly, yet comfortably inside the ear, the Fontopia in-the-ear-design allows you to enjoy music while you exercise, skate, or even dance! In addition, the Soft Rubber Earpiece minimizes stress on the ear while the Unique Bass Booster Earpiece Shape and Anti-bacterial Material offer wider frequency sound and worry-free wearing. Sony's Acoustic Twin Turbo Circuit for enhanced sound quality and a High-power Neodymium Magnet for maximum energy in minimum size are also included for your enjoyment.