Tips for buyers: The cause of howling/noise: The internal amplifier and the microphone are close to each other of the hearing aid, and the sound is continuously received and expanded, so it has a certain poibility of produce howling after power-on. At present, small hearing aids and high-power hearing aids on the market can hardly avoid howling, and only full-digital hearing aids can avoid howling. Ways to avoid howling/noise: 1. When the power is high (the amplified sound is large), howling is more likely to occur. Therefore, gradually increasing the volume from low can effectively avoid howling. 2. When the ear canal is completely sealed, there is no howling sound. Therefore, please use hearing aids after cleaning your ear canal, and test the earplugs from large to small to find the most suitable earplugs. 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, and then release it to fully extend the earplug. 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 ( 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 ackage included 1 x Hearing aid 4 x Earplug (Different sizes) 1 x User manual 1 x storage Box 1 x USB charging cable with the charge head Kindly Remind 1.Adjust volume to the minimum before wearing. 2.Choose an earplug of slightly bigger size to avoid whistler. 3.Increase volume gradually to avoid sudden increase in sound. 4.If you hear a howling, check the ear (silica gel) is appropriate and whether the size of plug is tight, the appropriate choice of earplugs and plugged, make sure no air leakage. 5.Keep the ear plug clean.