【About this item】: ● Rechargeable with Impressive Battery Time -- Our hearing amplifier adopts USB cyclic charging, you don't need to replace the battery frequently. It is fast charging and the charging time is about 4-6H(6H for first charge). ● Intelligent noise reduction -- Special processing of sounds of different frequencies, it can strengthen the human voice and weaken the environmental noise, which allows you to listen to what you want. ● Multi-frequency adjustment -- Adapt to a variety of environments and adjust sensitivity to suit different hearing ranges. ● Small and invisible -- It has invisible color close to skin and can be well hidden in your ears. We will come with three different size earplugs, which are more suitable for ear canal, it will satisfy all your imagination of hearing aids. (Tip: Please locate the earplug to fit the ear canal, otherwise it will cause noise.) ● Ergonomic and comfortable to wear -- Ergonomic and In-ear design, it is not easy to fall off. 24 hours long wearing without pain! the silicone earplugs are small, stable and comfortable to wear for a long time. You can wear it at will regardless of the left and right ears. 【How to Use】: Step 1: Before using switch the volume to the minimum position. Step 2: Put the ear hook on your ear, plug in the ear plug tightly. Step 3: Turn on the power,and adjuster the sound volume to get clear sound. Step 4: When you don't use it, please switch to"OFF" position. Warm reminder: Make sure the volume adjuster is at the minimum position before turn it on, otherwise the instant sound will make you uncomfortable. If you hear the whistling sound, please check whether you have plugged in the ear plug tightly. If it can't be plugged tightly, please change the other size plug. 【Product Details】: Max sound output: 110+5dB Sound gain: ≥30dB Total harmonic wave distortion: ≤10% Frequency range:300~4000Hz Input noise: ≤40dB Voltage: 3.7V The adapter output:5V Capacity: 30mah Current: ≤4mA 【What You Will Get】: A hearing amplifier; An USB cable; one cleaning brush; 3 ear plugs（Big/Middle/Small); an English user manual. 【Tips for buyers】: The cause of howling/noise:In order to make a small 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 possibility 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.