Four consecutive flashes indicate 4 bars of power, 3 flashes indicate 3 bars of power, and so on. It stay on when fully . 48V PHANTOM POWER: Mic preamp is compatible with a range of microphones, for use with both dynamic and condenser microphones. LOW NOISE: Microphone preamp features a , fully balanced circuit design that produces ultra low noise and clean sound, ensuring minimal noise and adding no coloration to your recordings. COMPACT AND : Microphone preamplifier is compact and , making it easy to carry and store. Perfect for home studios and professional studios, recording, podcasting and live streaming. Specification:B:Without Battery Color: Black Material: Metal Package Contents: 1 x Microphone Preamp 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.