Amplifies ambient sound to safe 82 dB – response technology reverts to passive hearing protector when noise reaches 82 dB. Sound amplification allows wearers to hear important communication, alarms/warning signals, co-workers’ voices. Ultraslim, lightweight earcup design and convenient folding design for easy storage. AUX input allows connection to external MP3 players or other audio devices for additional listening off the field. Includes 2 AAA batteries.