Bluetooth wireless transmission, the use of CSR master, DSP echo processing, are available inside the car, outside the ring with integrated speakers built-in speaker and microphone to eliminate echo 
 Bluetooth Specifications: Version2.0 
 Bluetooth Profile: Bluetooth stereo headset and hands-free 
 A2DP support 
 Transmitting power: Class 2 
 Wireless connection range: 10 meters 
 The operating frequency range :2.402-2 .480 GHz 
 Regulation voltage input: DC 5-6V 300-400mA 
 Built-in rechargeable lithium battery: 3.7V 800 mA 
 Normal charging time :8-10 hours 
 Standby time: 200 hours 
 :12-14 hours talk time