Play music out loud - anytime, anywhere with the Philips SBT10WHI/37 The built-in rechargeable battery lets you enjoy your personal music without the fuss of entangled power cords and the inconvenient search for an electrical outlet. Enjoy great music with the freedom of portability now. With its built-in microphone, this speaker also works as a speaker phone. When a call comes in, the music is put on pause and you can talk via the speaker. Call for a business meeting. Or, call your friend from a party. Either way, it works great. Neodynium is the best material for producing a strong magnetic field for greater sensitivity in a voice coil, better bass response and a pure balanced sound quality.