The two Concert BT speaker spheres from Terratec provide mobile stereo sound in an extraordinary design. Music playback is wireless via Bluetooth. Any device that meets at least the Bluetooth 2.1 standard can be used as an audio source. The connection remains stable up to a distance of 10 meters. For those without a Bluetooth source, MP3 players and similar devices can also be connected to the speakers via AUX cable. Each speaker delivers an output power of 1.5 watts RMS. The speakers can function together in wireless stereo mode or individually as mono speakers.

The speaker's battery allows for up to four hours of music enjoyment without an additional power source. It is charged using the included micro-USB cable. The music spheres themselves feature five control elements, allowing playback to be played, stopped, or paused, and the volume to be adjusted. The Terratec Concert BT has a diameter of nine centimeters and weighs only 274 grams.