The razor slim xtrm series features cooling headband, a noise rrduction rating (nrr) of 21 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.Includes 2 aaa batteries.Type: Electronic EarmuffColor: BlackNrr: 23 dBQuantity: 1Style: Over the HeadBattery: AAACompression Circuit: YesMaterial: Polymer