Loudhailer diameter: 9 mm  Frequency range:20~20000Hz
Sensitivity:110dB   Impedance:32 Ohm
Cable length:Approx 50mm   Maximum power input: 3-6mW
pulg(mm):3.5 Stereo
Power supply:build in 3.7V Lithium Battery
Charging:USB 5V adapter      Receiver distance:15meter