Hi- Tec Wireless Bluetooth Hands Free Speakerphone Car Bluetooth for Car Bluetooth Hands Free Kit (Black) Bluetooth version: V4.0, Frequency: 2.4GHz ~ 2.48GHz, Connetion distance: Up to 10m Automatic answering and voice prompt function. Support Hands-Free, Headset, A2DP, AVRCP profiles. Support Voice dialing / Last number redial / Call transfer / Volume adjustment. Built-in rechargeable battery, charged by the included charging cable.