The S8299B Motorola car kit is the perfect accessory for providing the convenience of hands-free operation in the vehicle and the ability to keep both hands on the wheel during conversation. The S8299B hands-free adapter will even conserve and charge the phone's battery for later portable use. S8299B Full duplex hands-free operation for more natural sounding hands-free conversations. S8299B Rapid NiMH battery charging - up to 90% capacity in about an hour with phone powered off. S8299B improves signal strength when used with an external antenna -- sold separately. With this kit we strongly suggest that you have a professional install the device. By having someone who knows little about car kits may result in damage to both your kit and vehicle.