The Howard Leight by Honeywell Impact Pro Sound Amplification Electronic Shooting Earmuff is designed for handgun and pistol shooters looking for maximum hearing protection. It carries a Noise Reduction Rating (NRR) of 30 in both on and off mode. When the electronic ear protection is switched on, it employs built-in directional microphones that amplify range commands and other ambient sounds to a safe 82 dB, providing more natural listening and enhanced communication. For additional shooting hearing protection, the earmuff also actively listens and automatically shuts off amplification when loud impulsive sounds like firearm discharges reach 82 dB. A padded headband features telescopic height adjustment for a comfortable, customized fit. Rubberized pressure points prevent gunstock scratching. An external audio jack lets you connect the shooting earmuff to an MP3 player, scanner or other audio source. The battery delivers approximately 350 hours of usage, and the automatic shut-off feature engages after 4 hours to help save battery life. All Howard Leight electronic earmuffs and safety eyewear are compatible for use with each other..