Portable Steering Wheel Mount BluetoothSpeakerphone version V2.1 + EDR (Enhanced Data Rates), with D.S.P. solution for echo cancellation and noise supression. Last number redials, answer, end a call reject a call, and transfer a call. Voice activated (subject to voice enabled phones). Battery type: Rechargeable Lithium DC 3.7V. General: Talk time up to 7 hours, Standby time up to 300 hours, and Charger time 2-3 hours.