Specifications:

High quality BTE hearing aid with USA speaker:
Max Sound Output: 129dB ± 4dB
Max Sound Gain: 45dB ± 5dB
Harmonic Wave Distortion: ≤5%
Frequency Range: 450~3500 hz
Input Noise: ≤30dB
Battery: A675 Zinc Air Battery
Working Voltage: dc1.5V
Working Current: ≤3mA
Color: As the picture shows
Item Size: 5.0 x 3.8 x 1.0 cm
Package Size: 9.0 x 7.5 x 3.2cm
Net Weight: 8g

Package included:

1 x F-998 Hearing aid
4 x Earplug (different sizes)
2 x A675 Zinc Air Battery
1 x User manual
1 x Box

Note:

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.
Keep the ear plug clean
Remove the battery if you don't use it for long time.