The Howard Leight by Honeywell Impact Sport Sound Amplification Electronic Earmuff keeps you protected from hazardous noise and connected to the environment. These earmuffs carry a Noise Reduction Rating (NRR) of 22 in both on and off mode. When the electronic ear protection is switched on, they employ built-in directional microphones that amplify ambient sounds to a safe 82 dB. As an added safety feature, they also actively listen and automatically shut off amplification when loud impulsive sounds like firearm discharges reach 82 dB. Patented Air Flow Control technology allows for a slim earcup design that ensures your firearm stock has clearance while shooting. The padded headband features telescopic height adjustment for a comfortable, customized fit. An external audio jack lets you connect the earmuff to an MP3 player, scanner or other audio source. Automatic shut-off after 4 hours helps save battery life. Protect yourself against hazardous gunfire noise without being left in silence.