Radians R3400 Quad Mic Stereo Jack Earmuffs - Green / BlackRadians R 3400 Quad Mic is an electronic sound amplification earmuff. Four independent microphones provide a full surround sound experience that amplifies low sound level noises while compressing sounds that exceed safe levels. Compact folding feature for easy storage. 3. 5mm stereo input jack and patch cable works with most smart devices. Electronic compression to protect hearing Amplifies environmental sounds for enhanced hearing Four microphones