1/2pcs Hearing Aid Adjustable Ear Sound Amplifier Volume Tone Listen Hearing Assistance Aid Kit
"Max Sound Output: 130dB ± 4dBMax Sound Gain: 38dB ± 5dBHarmonic Wave Distortion: ≤5%Frequency Range: 300~4000 hzInput Noise: ≤30 dBBattery: AG13 Working Voltage dc1.5V Working Current: ≤2.5mA "