1.This incredible new product is adopted with 3D sound coding technology, which maintains the Hi-Fi effects of MP3,MD, CD and TV. 2. It has been developed from frequency phase lock loop ethnology, which ensures stable frequency radiation while functioning at a distance of up to 30 meters with no dead areas. It operates through your automobile audio sounding equipment so that you can still enjoy Hi-Fi music. 3. It have 100 Operating frequency. Product Specifications: "1. Operating Distance: Up to 20 meters. " 2. Channel Isolation Ratio: ≥72db 3. Frequency Range: 20-1500Hz 4. Working Current: 45mA?0mA 5. Operating Frequency: Labeled on the unit 6. Output Current: 100 mA max (According to different model) Online service skype ID: robin926, ICQ ID: 300 732 551, MSN ID: cordialrobin contact person: Mr Robin Yang