X-136 Hearing Aid Earplug Convenient Sound Voice Amplifier Volume Adjustable Features: CE Approval, Volume control, ON/OFF switch, Pocket Hearing aid, Max Sound Output: 130±5 dB, Max Sound Gain: 50dB, Harmonic Wave Distortion: ≤5%, Frequency Range: 300~4000 Hz, Input Noise: ≤30 dB, Battery: 1 x AA battery, Working Voltage: dc1.5V, Working Current: ≤4mA, Color: As the picture shows.