Specifications Model: HD01 Max Output OSPL90: <=113dB+3dB OSPL90 HFA AV9: 103dB±3dB Max Sound Gain: 30dB±3dB Frequency Range: 300Hz-4500Hz Working Current: <=4mA Total Harmonic Distortion: <=5%+3% Working Tempreture: 0℃-40℃ Operating Voltage: 160mAh DC3.7V Use Time: About 35 hours Package Included: 1x Neckband Hearing Aids 6x Ear Covers 1x Usb Cable 1x User Manual 1x Packaging Box .