Walker's Razor Series Slim Lo Profile Electronic Earmuffs - Has Ultra Low profile ear cups, Rubberized coating, Two Hi gain omni directional microphones with an Audio input jack. Compact folding design and Comfort headband with metal wire frame. Sound dampening composite housing NRR 23 Sound activated compression 0.02 second reaction time Recessed volume control knob external battery door Operates on 2 AAA Batteries