Product Description 1. Compatible Bluetooth Specification V2.0+EDR. Class2 2. Operating Frequency Band: 2.4GHz ~ 2.48GHz unlicensed ISM band. 3. Support Multiple paired. (2 Bluetooth Phones can be paired meanwhile). 4. Integrated with echo cancellation and Noise suppressor. 5. One-Touch Answer, Call Rejection, Last Number Redial. 6. Advanced built-in louder speaker and microphone. 7. Battery type: Rechargeable Lithium DC 3.7V, 650maH (BL-5B). 8. Talk time: Up to 16 hours. 9. Charger time: 2~3hours.