Tips for buyers: Causes of whistling/noise: In order to make a small hearing aid, the internal amplifier and microphone are placed close to each other. The sound is continuously received and expanded, so there is a certain possibility of whistling after power-on. At present, small hearing aids and high-power hearing aids on the market are difficult to avoid whistling, and only fully functional digital hearing aids can avoid whistling. Ways to avoid whistling/noise: 1. When the power is large (the amplified sound is large), it is more likely to produce howling. Therefore, gradually increasing the bass volume can effectively prevent howling. 2. When the ear canal is completely closed, there is no whistling sound. So after cleaning the ear canal, put on the hearing aid, test the earplugs from large to small, find the most suitable earplugs, and ensure that there is no air leakage. 3. After the hearing aid enters the ear canal, it is recommended to push the hearing aid with your fingers and hold it for 1-2 seconds, then release it to fully extend the earphone. 4. In the shutdown state,turn the volume of the hearing aid to the lowest level, then insert it into the ear. Make sure that the earbud completely fills the ear. Then turn on the power button and slowly increase the volume to a suitable volume. 5. Users who have not heard the sound for a long time may cause hearing loss due to the long-term failure to hear the sound, resulting in the hearing aid still unable to hear the sound. Please persevere, continue to stimulate the growth of the hearing nerve, and you will hear after a while. If you are not sure whether your hearing aid is working properly, you can try the product on a person with normal hearing. 6. Please pay attention to cleaning the ear canal and keep the earplugs clean. In addition:If you do not know how to use it or there is a problem with your hearing aid, please do not rush to leave a negative review and contact us. Thank you. Feature 1. Mini BTE design 2. High power with chip noise reduction 3. 4 modes of operation, multifunctional design 4. Low power reminder, USB Rechargeable( Do not need to change battery ) 5. Charging 4-6Hours, working up 80 hours Specification Product Name: Rechargeable BTE Hearing Aid Color: Beige/Blue with charger head Charger: DC 5V150mA~1A Weight: App. 6.5g Size: 15x40x10mm Maximum Output: 129+4dB Maximum Gain: 38±5dB Total Harmonic Distortion: ≤5% Equivalent Input Noise: ≤28 Package included 1 x Hearing aid 4 x Earplug (Different sizes) 1 x User manual 1 x storage Box 1 x USB charging cablewith the charge head