Operating Range: 10-30 feet Channel Isolation Ratio >72db Operating Frequency Labeled on the unit Audio Frequency Range: 50Hz to 15Khz Output Current 1000mAmax * How to use: 1.Plug the unit into cigarette lighter in your car. 2.Connect input connector in the unit to your portable device output jack and adjust the portable device output to proper level by volume control 3.Turn the frequency of FM receiver in your car to the labeled on the unit and you can enjoy fantastic music in your portable device now.