... gift and promotion*On/Off Switch*Volume Control*Battery:AG13 or A675 (Zinc Air Battery)*Good sound quality, 30 meters away*Main ... ,test by the hearing aid test machine of Fonix 6500-C,Fonix 7000 and CR6128Remarks: It is not necessary to install ... :250~3800 hzEquiv Input Noise:≤30 dB Battery:AG13 or A675 (Zinc Air Battery)Working VoltageD. C. 1.5VWorking Current:≤4 mAMeasurement:6 ...