Feature: 1. SUITABLE MICROPHONE: Electret microphone amp input 3.5mm interface built in bias, can be connected to electret microphone head microphone or 3.5 interface capacitor microphone 2. POWER SUPPLY AND OPERATIONAL AMP: Adjustable gain electret microphone amp power supply is DC5‑12V, using the rail to rail operational amp MC33202 3. ABOUT INTERFACE: Sound preamplifier output adopt 3.5mm interface, can be connected to other sound device microphone interface or auxiliary, LINE and other line input interface, can not be connected to headphones listening 4. OUTPUT PORTS: After the microphone and music are amplified, they can be output independently or mixed output. There are three output ports in total, and the mixed output port can directly drive headphones to listen 5. GAIN AND POWER SUPPLY: Condenser microphone amp amplification gain 0‑20db adjustable, built in 150mah capacity lithium battery, charging with mobile phone charger, once charging can be used continuously for more than 10 hours Specification: Item Type: Electret Microphone Amp Material: Aluminum alloy Power Supply: 3.7V lithium battery 150mah Input Interface: 3.5mm Power Voltage: DC5-12V. Package List: 1 x Electret Microphone Amp 1 x Charging Cable