Automatic noise protection - amplification automatically shuts off at 82dB attenuating impulse and continuous noise. Sound amplification - sound is amplified to deliver superior directional sound quality in stereo. Headband adjusts for a secure, non-slip fit. Single knob control for on /off and volume; power automatically shuts off after 4 hours of use. Equipped with an external audio input that allows you to connect to your own audio source To capture low level sound, the Impact Sport employs built-in microphones that amplify range commands and other important sounds. Users enjoy full, clear directional hearing in stereo. For protection, the Impact Sport actively listens and automatically shuts off amplification whenever harmful sound levels are reached. The earmuffs effectively block any noise, continuous or impulse, of 82dB or more. External audio input allows you to connect your IPOD or other audio source. Black leatherette headband with hunter green earcups. Snap-on lid for quick and easy battery replacement. Outstanding battery lifetime. Includes 2 AAA batteries. Compact Fold design for convenient storage. Noise reduction rating: NRR 22 provides excellent attenuation in a sporting environment .