Tips for buyers: The cause of howling/noise: In order to make a mini size hearing aid, the internal amplifier and the microphone are close to each other. 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. Peak Gain(dB): 42dB, Suitable for mild to moderate severe hearing lo (Reference hearing lo map) 2. Mini-size hearing aid is a powerful unit with noise reduction feature, perfect for those who want precise sound amplification, it is so small that others will hardly notice. 3. Light and comfortable: device is extremely light, it can be comfortably worn in either ear. With the spring like connection, it can fit in all sizes of ears. 4. A10 battery, low power consumption. Long time service which good for travel. 5. Analog, digital hearing aid, 2/4/6 channels are available; 6. Easy to Operate: Medium size in-the-ear hearing aids, with large volume buttons and battery compartment, easy to operate for the elderly and adults. 7. If the ear dome is not completely fill into ear canal or air leaks at the ear dome, which will causes a annoying whistle. We give 3 different sizes of earplugs to reduce howling and noise. 8. Gift bundled: We will give a hearing aid box to carry.Every set contains matching battery, earbuds and cleaning brush.Will be great gifts for your friends or families. Product parameters Peak OSPL 90 ( dB SPL): 107.2dB HAF OSPL 90 ( dB SPL): 104dB Peak Gain(dB) : 45dB HAF/FOG Gain (dB) : 37dB Frequency range(Hz) : 200-5700Hz Distortion : 500Hz : 3% 800Hz : 3% 1600Hz: 3% Specification Product Name: CIC Hearing Aid Color: Blue(left)/Red(right) Battery: A10 battery Weight: total 70g Package included 1 Hearing aid 1 Storage box 3 Earmuffs(different sizes) 1 Matching battery (A10) 1 Hearing Aid Cleaning Brush 1 Instructions (Please make sure has read the manual before using). Instructions 1. Clean the ear canal before use. 2. Insert the battery,turn the botton to N. 3. When using it for the first time, please turn the volume to the minimum and then slowly increase it. 4. Try and select suitable ear dome. Install the ear dome and make sure it fits snugly. 5. Insert the hearing aid into the ear canal,adjust its position in the ear canal until the soft eartip is fully deployed and fill the ear canal.