The Howard Leight Impact Pro Industrial earmuff has a high passive rating (30 NRR; 33 SNR) and is built to protect worker's hearing while allowing them to have environmental awareness. All day comfort is provided by the textile headband and cushioned muffs. Features and benefits: -Directional stereo microphones amplify ambient sounds, such as alarms/warning, signals, and conversations whilst suppressing loud, impact noises down to a safe level of 82dB -Audio/auxiliary jack enables connection to a personal listening device -On/off and volume control button -Requires 2x AA batteries