Impact Sport Bolt electronic earmuffs amplify ambient sound while automatically blocking hazardous noise. All new digital compression circuitry offers lightning fast attack time of .5 milliseconds and 5X Sound Amplification. For protection, the Impact Sport BOLT actively listens and automatically shuts off amplification whenever harmful sound levels are reached. The earmuffs effectively block any noise, continuous or impulse, 82 dB or higher. To enhance low-level sound, the Impact Sport BOLT employs built-in microphones that amplify range commands and other ambient sounds. Slim earmuff design makes this a very versatile earmuff for most shooting environments. 4-hour auto shut-off preserves battery life. Convenient folding design for easy storage. Easy access to the external battery compartment. Water resistant. NRR 22. Black earcups.