Sell 2021 Mini Hearing aid Invisible Sound Amplifier Volume Adjustable Ear Hearing Assistant Helper for best price

Sound Output (SSPL) 120+3db Sound Gain (DSPL) 25±5db E0 Input Noise 32db Frequency Range 450Hz~5000Hz Working Current 2mA Harmonic Wave Distortion(THD) 4% Battery/Cell Type A10 Voltage D.C.1.3V There are Whistle as you put the battery into the hearing aid . Please donot worry .because the air presure will make Whistle. 1.Please adjust lower volume . 2.Choose the suitable ear plug 3.Make sure if you put the earplug tightly,sound leak will make the Whistle.