(Note:For buyers in Australia country, due to the laws and regulations of your country, button batteries cannot enter your country, We don't put batteries in the hearing aid package) FEIE ear amplifier aparat analog hook hearing aid aids the ear listens S-520 adjustable tone Sound Enhancer Medical Equipment Feature: Easy to hide and comfortably wear, This hearing device is unmatched in comfort and style. It is designed to be stylish and easily blend in with your body. Built-in sounder, clear voice, save electricity. Wear nature and comfortable, will not oppre the ear. This hearing amplifier comes with an excellent built-in digital noise reduction controller, allowing you to hear the person next to you with ease even in a noisy room. Help people with hearing impairment to hear sound and voice. Technical Parameters: Max Out:1264dB Max Gain:505dB Harmonic Dist:5% Frequency Range:300Hz ~ 3500Hz Equivalent Input Noise : 32 dB Standard Battery: A675 button cell Hearing aid coil sensitivity >100dB Working voltage: 1.5V Current: 4mA Product Weight: 8g Product Size: 5.1*3*1cm Target user: People with moderate to severe hearing lo are available (average hearing lo not exceed 80dB) Packing list: Principal machine * 1 Earplugs * 3 Cleaning sweeper * 1 Warranty card * 1 User manual in English * 1 Battery* 1 Note That is normally situation that hearing aid make whistle noise . About noise , you can do this steps to remove it . -Adjust volume to the minimum before wearing. -Choose an earplug of slightly bigger size to avoid whistler. -Increase volume gradually to avoid sudden increase in sound. -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.