Features: 1. Digital processing chip, ultra-low power design, (zinc air battery A13)600 hours last use of one battery 2. Ear hook and shell copper column connection, solid structure. 3. high-fidelity microphone, small distortion, low noise; 4. Comfortable adjustment, can reduce noise. 5. New digital hearing aids, beautifully designed for moderate to severe hearing use. Technical Parameters: Maximum saturated sound pressure level (dB):≤132dB + 3dB High frequency average :127dB ± 4dB Full sound gain (dB):50dB ± 5dB Equivalent input noise:≤ 32dB Total harmonic distortion:≤ 10% Frequency response range:450Hz ~ 3000Hz Rated supply current:≤ 5mA Instruction: - Adjust volume to the minimum before wearing. - Choose an earplug of slightly bigger size to avoid whistler. - Increase volume gradually to avoid sudden increase in sound. -If you hear a howling,check the ear (silica gel) is appropriate and whether the size of plug is tight,the appropriate choice of earplugs and plugged, make sure no air leakage. - Please regularly clean the ear plugs or ear molds in order to ensure the normaluse of hearing aids. - Use for long periods of time, please remove the batteries to prevent battery roterosion hearing aid components Package content: 1 x Hearing Aid: 1 x Cleaning Brush 4 x Earplugs(Different Size); 1 x Instruction manual(in English) 2pcs sound tube only 1pcs battery please note not 2pcs batteries.