What's in the box:

Microphone Amplifier Volume Adjustment Real-time Monitor Functions with Monitor Earphone 3.5mm to 6.5mm Audio Adapter (Standard)

Features:
The item can adjust the volume level of your microphone(3.5mm audio plug), and can real-time monitor the input sound from microphone.
Powered by 1pc 1.5V AAA alkaline dry battery (not included). Adopt the low power circuit design, making its runtime up to 10-15 hours.
Adopt the low noise circuit design, 16-level electronic volume control, long-lasting and durable in use.
Built-in phone/camera microphone system switching circuit, compatible with multiple video/ sound recording devices.
Use superior 3.5mm nut interface socket, ensuring reliable connection.

Specifications:
Model: EY-580S
Gain: -18dB~+12dB (audio line output); -5dB~+25dB (earphone monitoring output)
Frequency Response: 20Hz~20KHz
SNR (Signal to Noise Ratio): >92d
Degree of Distortion: <0> Power: 105mW(earphone monitoring output)
Volume Adjustment: 16-level (each level 2dB)
Working Voltage: DC 1.5V
Working Current: 30mA (static state)
Cable Length: Approx. 1 meter
Item Size: 8 * 3.3 * 1.5cm / 3.1 * 1.3 * 0.6inch
Net Weight: 49g / 1.7oz
Package Size: 17 * 10 * 4.5cm / 6.7 * 3.9 * 1.8inch
Package Weight: 140g / 4.9oz

Packing List:
1 * Microphone Amplifier
1 * Monitor Earphone
1 * 3.5mm to 6.5mm Audio Adapter
1 * Carrying Case

Note:
AAA battery is not included.