Specification: 1. Driver: 15mm 2. Impedance: 9 OHM 3. Bluetooth version: Bluetooth 5.0 4. Output power: 40mW;Battery capacity 35MAH , charging box is 300mh . 5. Bluetooth distance: 10 meters 6. Frequency response: 20-20000Hz 7. Operating voltage range: 3.0V-4.2V 8. Powerful noise de-noising circuit (active noise reduction) 9. Charging time about 1-2 hours . 10. Talk time is about 2-3 hours (a pair of earphones use together ),music time about 2-3 hours (a pair of earphones use together ) , Charging box can charge for the earphons about 3-5 times.