Radians R-3200 Dual Mic is an electronic sound amplification earmuff. Two independent microphones pick up and amplify 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 Two microphones LED On / Off indicator light Adjustable headband folds for compact storage 3.5mm stereo input jack and patch cable (included) enable playback from smartphone or digital audio player NRR 23 dB 2-AAA batteries required (not included)