The Stereo Electronic Hearing Protector automatically and instantaneously shuts down when decibel levels exceed 85 Db. When the decibel level falls below 85 Db, the control circuit restores normal operation. Its a great solution for noisy work areas, indoors or out. The Electronic Hearing Protector permits normal conversational levels, yet blocks out potentially hazardous noises from machinery, chainsaws, shooting sports, and others. The volume level can be adjusted with the on/off control switch. Also features 2 built-in microphones, LED indicator, padded ear cushions and headband. Weighs only 12 ounces.