This amplifier is a great solution for those who has hearing problem or in need of precise sound amplification. They are unique and the best. Whether you love listening or playing music, or have some hearing issue, or just want to experience a new and exciting level of hearing, our amplifier is an optimal choice for you. Features - Color: Blue. - Material: Silicone. - Size: 3 x 2 x 1cm (LxWxH). - Help you hear the sound clearly and loudly, suitable for patients with mild to extremely severe hearing loss. - for watching movie, enjoying the drama, attending meeting, having class, and chatting with friends. - Work with A10 button cell battery (the battery is not included). - It will increase volume gradually, so please adjust volume to the minimum before wearing to avoid sudden increase in sound. Specifications Type: Hearing Amplifier. Model: ZDC-901A. Left Ear Side Color: Blue. Calibration: Automatic. Max. saturated sound pressure level (OSPL90): 118. High frequency average(OSPL90): 109. Full sound gain(1600HZ): 32. Equivalent input noise: le;28. Total harmonic wave distortion: 8%. Frequency response range: 300-3500. Power Voltage: 1.4V, +5%-10% relative error. Note: 1.Keep the ear plug clean. 2.Do not wear on swimming or rainy days. 3.Remove the battery if you don't use it for long time.