Radians R-3400 Quad Mic Electronic Earmuff - Military Green - Radians 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 LED On / Off indicator light Adjustable headband folds for compact storage 3.5mm stereo input jack and patch cable enable playback from smartphone or digital audio player NRR 24 dB (2) two AAA batteries required