Sony Fontopia MDRE829V Stereo Earphone Wired Connectivity Neodymium Magnets pack more magnetic energy per ounce than conventional ferrite, samarium cobalt or aluminum magnets and produce powerful bass and clear treble sound PET Diaphragms ensure high rigidity for minimum distortion and low mass for excellent high-frequency response Sony Acoustic Twin Turbo Circuit uses sound chamber and ducts for improved efficiency; gets high sonic output from your portable stereo Compact Winding Case Supplied neatly stores the ear-buds and headphone cord when not in use; ideal for carrying in pocket or purse Silent Cap virtually confines headphone sound to your ears only and helps ensure that your music does not disturb others