Add the safety and convenience of Bluetooth® to a vehicle that doesn’t have it from the factory. Attaches to your sunvisor for convenient operation and optimum microphone/speaker location. Supports up to two phones with auto power-off when Bluetooth connection is lost (ie, when you walk away from the car with your phone). Internal rechargeable battery with up to 30-days standby time. Added safety with great convenience.Features:- Bluetooth® 4.0- Digital power amplifier- Rechargeable battery- 30 days standby on full charge- Connect two phones simultaneously- Turns off automatically when no Bluetooth connection detected- Voice answer- Noise reduction microphone- Turns on automatically when car door is opened/shutSpecifications:Output Power: 2WCharging Voltage: 5VDCSNR: ≥ 70dBFrequency Response: 180Hz - 16kHzDistortion: 0.5%Impedance: 8?Battery: 3.7V @ 600mAh rechargeable Lithium