Walker's Razor Slim Lo Profile Electronic Earmuffs -The Razor series feature 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 hunting partners, even when shots are being fired around you. Ultra low profile ear cups Audio input jack Low noise/ frequency tuned for natural sound clarity Volume control Sound dampening composite housing Two hi gain omnidirectional microphones Rubberized coating Includes 2 AAA batteries