AudioGeek R400 Distortion-Free Aluminum Wireless Speaker (High-Fidelity) Bluetooth 4.0 / Dual Driver 10W Output (Powered by ClearSound Technology) Distortion-free sound from the R400 HiFi speaker is the result of professional tuning and obsessive attention to every component within. Universally compatible Bluetooth 4.0, Speaker unit: diameter 45mm, inner magnetic 4,5W*2 Built-in Mic and speakerphone allow you to shift from music to phone calls seamlessly. Internal 4000mAh battery provides plenty of portable power for all day use. (6+ Hours) Guaranteed to blow you away or your money back!