Hearing amplifier

Max sound output: 130±5dB Sound gain: ≥50dB Total harmonic wave distortion: ≤10% Frequency range: 300~4000Hz Input noise: ≤30dB Voltage: DC 1.5V Current: ≤4mAUsage Open the cartridge cover, put the battery in the correct position. Zine Air battery is the best choice and has a longer life. Before using, make sure that power is turned off, or make the volume to “l”. Put the ear hook on your ear, plug in the ear tightly. Note:The unit is on “off” position, and volume is on “l”, otherwise the instant sound will make you uncomfortable. Turn the power, and adjust the sound volume to get clear sound, If you hear the whistling sound, please check whether you have plugged in the earplug tightly. If it can’t be plugged tightly, please change the other size plug.