You can wear this earphone behind your neck, leaving total freeness to your head. You also can connect this earphoen to all rangs of media to enjoy your ideal music, whenever you are working or moving on the way. And its EARPHONE ELECTRICAL CHARACTERISTIC as follows: Driver Unit: Ø10 Impedance:16Ω Sensitivity: 101db (at 1KHZ 0.126V) MAX. Input power: 10mW Frequency range: 20Hz~20KHz Distortion: ≤5% (1mW 1KHz) Plug: 3.5mm