banglijian hearing amplifier rechargeable ziv-201 digital noise reduction and feedback cancellation small size banglijian our hearing amplifier is convenient and durable to wear. it runs with high quality rechargeable lithium battery, its great battery runs around 20-24 hours continuously after fully charged. it can be charged via usb cable.<br/> <br/> frequently asked questions<br/> <br/> question one: why there is the whistling sound?<br/> answer:<br/> 1. the ear plug is too small.<br/> 2. the ear plug is not really inserted into the ear canal.<br/> 3. the sound tube isn't connected tightly with the ear plug.<br/> 4. the sound tube isn't connected tightly with the ear hook.<br/> question two: why there is noise?<br/>answer:<br/> if you hear noise, it may be the sound of the current,<br/> which needs time to adapt to, please understand.<br/> if you increase the volume, the sound of current will also<br/> be increased more obviously like the sound of wind.<br/> if it still can not help, please try to switch the programs.<br/> <br/> generally, it takes 20 -30 days to get used to the sound. please try to adapt to it. if you cann't, our quality commitment is "3 months hassle free return policy, 3 year on hassle warranty!".<br/> <br/> warm prompt: <br/>when you first use this product, please charge the batter fully.<br/>please turn off the power before assembling the hearing amplifier. <br/> <br/> package includes:<br/> 1 banglijian hearing amplifier(psap)<br/> 1 shockproof case<br/> 3 ear plugs (small, medium, large)<br/> 1 sound tube (for a better customer experience, you will receive 2 more sound tubes)<br/> 1 cleaning brush<br/> 1 power adapter<br/> 1 usb cable ( can use power bank-5v,1a output )<br/> 1 user manual<br/>