Your all-in-one wireless portable speaker bluetooth USB built-in microphone for calls 20W, rechargeable battery. Works with any bluetooth-enabled deviceworks with any bluetooth-enabled device bluetooth is a short range wireless communication technology that is both robust and energy-efficient. The technology allows easy wireless connection to other bluetooth devices, so you can play your favorite music from any smartphones, tablets or even laptops including ipod or iphone on bluetooth-enabled speaker easily. 20W RMS total output power20w rms total output power this system has 20W RMS total output power. Rms refers to root mean square which is a typical measurement of audio power, or rather, the electrical power transferred from an audio amplifier to a loudspeaker, which is measured in watts. The amount of electrical power delivered to the loudspeaker and its sensitivity determines the sound power that is generated. The higher the wattage, the better the sound power emitted by the speaker. Usb direct for easy mp3 music playbackusb direct for easy mp3 music playback thanks to the complete file transferability, you can easily enjoy the convenience and fun of accessing more digital music via the built-in usb direbuilt-in digital fm radio digital radio is, on top of fm analog transmission, a new way of broadcasting radio via a network of terrestrial transmitters. It provides listeners with more choices and information delivered in clear, crackle-free sound quality. The technology allows the receiver to lock on to the strongest signal it can be find. With digital stations there are no frequencies to remember, and sets are tuned by station name, so there is no returning on the move.