Specification:<br />Convenient wear<br />Low noise・ low distortion;<br />For people with severe hearing loss;<br />Product use hearing assistive devices.<br />The scope of application of gas conduction hearing disorders.<br />Taboos otitis media or ear suppuration who are disabled.<br />Features:<br />Maximum sound output: 130   5dB    <br />Sound gain:   50dB    <br />Total harmonic distortion:   5%   <br />Frequency range: 300Hz ~ 40000Hz    <br />Input Noise:   30 dB    <br />Operating voltage: 1.5V    <br />Battery model LR44 <br />Current:   4mA<br />Weight: 74g<br />Instructions