Features:-There are five levels of volume control with beep prompts.-Equipped with portable charging case, 3-4 hours to full power of the case, can offer totally 36-90 hours of use. -The operation is simple, long press to turn on and short press to adjust the volume, making it convenient for the elderly to use.-High-definition sound quality enables barrier-free communication, and the full-scale gain is greater than 35dB.-The cochlear ergonomic design is comfortable to wear and can be used for a long time.Specification:Material: ABS+siliconeMAX OSPL90 (dB SPL): ≤115dB+3dBHFA OSPL90 (dB SPL): 110dB±4dBFOG：30dB±3dBHFA FOG：29dB±3dBFrequency range: F1<400Hz, F2>4700HzTHD 500Hz：≤5+3%THD 800Hz: ≤5+3%THD 1600Hz: ≤5+.