GoldenPlayer Wireless Over-Ear Headphone MODEL: GP-M6BT-BK Wireless Version: V5.0 Working Distance Range: 10m (33ft.) Built-in Rechargeable Lithium Battery: 350mAh Charging Voltage: DC 4.2-5.5V Charging Time: about 2 hours Talking/Music Time: about 25 hours Driver: 2 x 40mm Impedance: 60Ω