Portable Rechargeable Invisible Hearing Aid US Plug Blue

1 Material ABS2 USB charging port3 Lightweight and comfortable to wear4 Built in lithium battery 30mAh5 Charging time about 2 hours6 Working voltage d c 1 2V7 Working time about 40 hours8 Frequency range 500 5000MHz9 Input noise less than or equal to 32dB10 Working current less than or equal to 1 2mA11 Total harmonic distortion less than or equal to 10 Sound output 129 3dB13 Sound gain greater than or equal to 40dB 5dB14 Net weight 6g