If your lifestyle requires ultra-compact portability, the TDK BP100 earphone is an excellent choice. The wind-up carrying case eliminates the threat of cord tangles while protecting the earphone and making them easy to stash in a messenger bag, purse or even your pocket. Like all TDK earphone, the BP-100 delivers full-range frequency response with bass reaching all the way down to 20Hz. Never miss a beat with the TDK BP-100 earphone.