B39 Wireless Bluetooth V5.0 Headset 1. Drive: 40mm 2. Impedance: 32 OHM 3. Bluetooth version: V5.0 4. Bluetooth frequency band: 2.4GHz 5. Power level: CLASS II 6. Bluetooth distance: barrier-free 10 meters 7. Frequency response: 20-20000Hz 8. With A2DPAVRCP high-quality stereo audio transmission and remote control protocol 9. Charging time is about 1 hour 10. Talk time is about 10-12 hours 11. Music time is about 2-3 hours 12. Standby time is about 120 hours 13. Battery capacity 400mah250mah 14. Charging power supply: DC5V power supply [round hole interface] (computer USB port, mobile phone charger, car charger) 15. Compatible mobile phone: compatible with Android, Apple, Microsoft, Saipan system 99 percent of mobile phones with Bluetooth function Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.