Specifications: FM Radio Broadcast Online Chat Wireless or wired headphone Suitable for sound receiving from electronic products with audio output such as TV,computer,DVD OR VCD. Trumpet: 27mm Impedance: 32Ohms Frequency Response: 20Hz-20KHz Sensitivity: 102dB Transmitting frequency: 83-108MHZ Max receiving range: 30m Power supply: AAA DC 1.5V batteries 2pcs