Color Music. Not just a hue, but your personality. "To all appearance the range of our senses is exactly the same, and nature gives us as many sounds as colors." -Louis-Bertrand Castel(1723) We believe that colors should be within music, but sometimes it needs to be presented. Not just a hue, but your personality, uncompromising attitude to reality. Design inspiration of B2 Bluetooth headset was inspired by the theory of color music from L.B. Castel in 18th-century, the French mathematician and philosopher. We hope that different colors of our headsets will help you enjoy your music freely and often immersed in happiness. It has been considered that when listening to different music, humans will associate it with a specific color. The theory of color music had provided a musical direction for the theory of color and affected Rosseau and Voltaire at the same time. Just for the color Long-lasting comfort Foldable and stretchable design Drive units made for pure sound Perfect sound and talk Spec: Bluetooth Version: V4.0 Support: A2DP、AVRCP、HSP、HFP RF Frequency Range: 2402 ~ 2480MHz（ISM BAND） Transmitting Power: Class2 RF Sensitivity: < -85dBm (PER 1 %) Operating Distance: Up to 10m (free space) Frequency Response: 20-20kHz Talk Time: Up to 33hrs Bluetooth Music playtime: Up to 33hrs Standby Time: Up to 1300hrs(50days) Charging Time: 1-2hrs Charging Port: Micro-USB 5PINS