Main Features:<br />Put the plug into the socket of the voice amplifier<br />select the suitable earphone adaptor to connect<br />The switch should be turned to the "off" position when the apparatus is not used， it will make a longer battery life<br />The volume is adjustable by turning the control knob， from minimum position 1 to maximum position 8<br />It is important to increase the volume control gradually<br /><br />    Specifications<br />Specification<br />	 Brand: XINGMA                                                  <br />                        Model: XM-999                                                  <br />                        Power supply: 1 x AA Battery (Not included)                                                  <br />                        Wearing  type : Wired earphone                                                  <br />                        Max sound output: 133 ± 4dB                                                  <br />                        Max sound gain: 48 ± 5dB                                                  <br />                        Total harmonic wave distortion: ≤ 8%                                                  <br />                        Input noise: ≤ 30dB                                                	<br />Dimension/Weight<br />	 Product Weight: 0.024 kg                                                  <br />                        Package Weight: 0.150 kg                                                  <br />                        Product Size (L x W x H): 6.9 x 4.2 x 1.8 cm / 2.71 x 1.65 x 0.7 inches                                                  <br />                        Package Size (L x W x H): 11.3 x 9.8 x 4.2 cm                                                	<br />Package Contents<br />	 Package Contents: 1 x Hearing Aid， 1 x Connector Wire， 1 x Earplug， 3 x Earplug Cover， 1 x User Manual                                                	<br /><br /><br /><br />                                                <br />