Head-mounted Wireless Bluetooth Stereo Headset, A70 Black, A70 Black Red, A70 Brown1. Bluetooth 5. 0, stable core upgrade, free listening, more stable transmission signal, less sound loss, and switching between calls and music at will. 2. 50 hours of powerful battery life to listen to music. 3. The earmuffs rotate by 90 degrees, which is easy for unilateral wireless monitoring. 4. Bluetooth: 5. 0 5. Battery capacity: 650 mA 6. Speaker: 40 mm 7. Impedance: 32 ohms 8. Sensitivity: 110dB+3dB 9. Frequency response: 20Hz 20KHz 10.