1. and high-quality products. 2. Made of high-quality materials, and practical. 3. Fine workmanship and good performance. 4. Long service life. 5. A special amplifier board for electret microphones powered by 48V phantom power, universal and single-point electret microphones. By matching the microphone with different parameters, it can be used for karaoke, recording, conference speech and so on. The bottom noise of the amplifier board has a lot to do with the microphone. It is recommended to use a low-noise electret microphone to achieve the desired effect. Type of microphone used:electret microphone Frequency response and sensitivity:(depending on the use of microphone) Output impedance:250 ohms Sound pressure level:125db Signal to noise ratio:60db Power supply:15-48v phantom power Working current:about 3.2ma Board size:45mmx15.82mm (cannon head part is not included) Colour:Black Material:PC+Metal Package Contents: 4 x Microphone amplifier board Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.