1The built-in orienteering microphone can amplify the range instructions and other ambient sounds to a secure 82 dB, providing more natural listening and enhanced communications. 2Active monitoring and auto-close amplification when the ambient sound reaches 82 dB. 3Integrated power/ volume knob - Includes AUX input and 3.5 mm connecting cable for MP3 player and scanner. 4Compact folding design is convenient for storage. 5With auto power off function (when no operation after 4 hours) to extend battery life.Features: The built-in orienteering microphone can amplify the range instructions and other ambient sounds to a secure 82 dB, providing more natural listening and enhanced communications. Active monitoring and auto-close amplification when the ambient sound reaches 82 dB. With noise reduction level (NRR) of 22dB. Can be used for the cleaning of the stock Adjustable headband to ensure safety. Compact folding design is convenient for storage. Integrated power/ volume knob - Includes AUX input and 3.5 mm connecting cable for MP3 player and scanner. With auto power off function (when no operation after 4 hours) to extend battery life. Long battery capacity to play for about 350 hours. Specification: Type: Noise-Proof Earmuff Product Weight: Approx. 1LB Product size: Approx. 11 * 10 * 4CM(Single earplug)Battery type: 2 AAA batteries (NOT Included)Style: earmuffsMaterial: ABS plasticEnergy-source: Battery powered Sound level: 24 dBMeasurement System: English/ StandardSpecial function noise reduction level (NRR): 22 dBUsage: Passive protectionIncluded component: Impact Sport earmuffs, 3.5 audio connectionsWhether include battery: NOAverage battery life: about 350 hoursPackage list: 1 * Noise-proof Earmuff 1 * 3.5MM Audio Cable 1 * Instruction Manual Note: 1. Please note that it requires 2 AAA batteries, which are NOT included. 2. Please allow slight error due to manual measurement. Thanks for your kind understanding.