Walker's Freedom Series Walker's Logo Electronic Earmuff - Featuring Walker's New Line of the Freedom Series! This series has a Noise Reduction Rating (NRR) of 23 dB, and utilized sound activated compression (SAC) of 0.02 seconds. SAC is a special electronic circuitry that will compress gun shots and other loud noises down to a safe level, without completely shutting the noise off. This allows you to hear range commands or communicate with your shooting or hunting partners, even when shots are being fired around you. Ultra low-profile ear cups Rubberized coating Two hi gain omni directional microphones Audio input jack Low noise/frequency tuned for natural sound clarity Volume control Compact folding design 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 included